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SOLVED
Thank you #New Dev and #Joakim Danielson for your help. I used #Joakim Danielson's answer to improve my code.
I have an extension method to assign accessibilityIdentifiers to views based on a given String Enum. I updated the method to directly accept String Enum Cases as a parameter, thus COMPLETELY eliminating the need for the AccessibilityId enum class as shown below, awesome!
Changes
Before:
.accessibility(identifier: .home(.clickButton))
// Simplified for StackOverflow.
// Imagine 20 more cases..
enum AccessibilityId {
case home(HomeId)
var rawValue: String {
switch self {
case .home(let id):
return id.rawValue
}
}
}
extension View {
func accessibility(identifier: AccessibilityId) -> ModifiedContent<Self, AccessibilityAttachmentModifier> {
self.accessibility(identifier: identifier.rawValue)
}
}
After:
.accessibility(identifier: HomeId.clickButton)
extension View {
func accessibility<T: RawRepresentable>(identifier: T) -> ModifiedContent<Self, AccessibilityAttachmentModifier> where T.RawValue == String {
self.accessibility(identifier: identifier.rawValue)
}
}
---------------------------------------------------------------
Original Question
What I have
enum Item {
case animal(AnimalId)
case vehicle(VehicleId)
case food(FoodId)
var rawValue: String {
switch self {
case .animal(let id):
return id.rawValue
case .vehicle(let id):
return id.rawValue
case .food(let id):
return id.rawValue
}
}
}
enum AnimalId: String {
case cat
case dog
}
// etc.
// Imagine more cases and more enums.
What I want
enum Item {
case animal(AnimalId)
case vehicle(VehicleId)
case food(FoodId)
var rawValue: String {
switch self {
case self as StringEnum:
return id.rawValue
default:
return ""
}
}
}
Usage
func test() {
foo(.animal(.cat))
foo(.vehicle(.plane))
foo(.food(.tacos))
}
func foo(_ item: Item) {
print(item.rawValue)
}
I am happy with the usage, but I'd like to reduce the amount of duplicate cases in the given switch statement. Notice how they all have return id.rawValue. The above is just an example, in reality I have around 30 cases.
My Question
Is there a way for me to catch all Nested String Enums in a single switch or let case to reduce the duplicate code I have to write without losing the intended usage?
Thank you for your efforts, I hope to find an improvement for my code!
Here is a solution that is not based on Item being an enum but instead a generic struct
struct Item<T: RawRepresentable> where T.RawValue == String {
let thing: T
var rawValue: String {
thing.rawValue
}
}
With this solution you don't need to change your other enums.
Example
let item1 = Item(thing: AnimalId.cat)
let item2 = Item(thing: VehicleId.car)
print(item1.rawValue, item2.rawValue)
outputs
cat car
You need something common between all these associated values, like a conformance to a shared protocol, e.g. protocol RawStringValue:
protocol RawStringValue {
var rawValue: String { get }
}
// String enums already conform without any extra implementation
extension AnimalId: RawStringValue {}
extension VehicleId: RawStringValue {}
extension FoodId: RawStringValue {}
Then you could create a switch self inside like so:
var rawValue: String {
switch self {
case .animal (let id as RawStringValue),
.vehicle (let id as RawStringValue),
.food (let id as RawStringValue):
return id.rawValue
}
}
That being said, enum with associated values isn't the most convenient type to work with, so be sure that it's the right choice.
I love that Swift allows for the use of enum methods. I'm trying to work with a method but am looking for a more extensible method of doing this:
enum CopyState{
case binary, hex, both
init(){
self = .both
}
mutating func next() {
if self == .binary{
self = .hex
} else if self == .hex {
self = .both
} else if self == .both{
self = .binary
}
}
}
var state = CopyState()
state.next()
I'd like to essentially cast the enum to an integer and increment it modulo the number of total enum options
Adding or removing enum options is a hassle (I'm using a last() and a next() method).
Update Starting with Swift 4.2 you can make use of the newly added support CaseIterable protocol, which adds compiler support for generating a list of all cases for an enum. Though #ninestones's comment pointed put that we are not guaranteed for allCases to return the cases in the same order as defined, the synthesized implementation does this, and it's unlikely that definition will change.
Your enum could then look something like this (no more hardcoded start value):
enum CopyState: CaseIterable {
case binary, hex, both
mutating func next() {
let allCases = type(of: self).allCases
self = allCases[(allCases.index(of: self)! + 1) % allCases.count]
}
}
You can make this piece of functionality available to all CaseIterable enums:
extension CaseIterable where Self: Equatable {
mutating func next() {
let allCases = Self.allCases
// just a sanity check, as the possibility of a enum case to not be
// present in `allCases` is quite low
guard let selfIndex = allCases.index(of: self) else { return }
let nextIndex = Self.allCases.index(after: selfIndex)
self = allCases[nextIndex == allCases.endIndex ? allCases.startIndex : nextIndex]
}
}
enum CopyState: CaseIterable {
case binary, hex, both
}
var state = CopyState.hex
state.next()
print(state) // both
state.next()
print(state) // binary
Or, a little bit more verbose, but with a better separation of concerns:
extension Collection {
// adding support for computing indexes in a circular fashion
func circularIndex(after i: Index) -> Index {
let nextIndex = index(after: i)
return nextIndex == endIndex ? startIndex : nextIndex
}
}
extension Collection where Element: Equatable {
// adding support for retrieving the next element in a circular fashion
func circularElement(after element: Element) -> Element? {
return index(of: element).map { self[circularIndex(after: $0)] }
}
}
// Protocol to allow iterating in place (similar to a type conforming to both Sequence and IteratorProtocol)
protocol InPlaceIterable {
mutating func next()
}
extension InPlaceIterable where Self: CaseIterable, Self: Equatable {
// adding default implementation for enums
mutating func next() {
self = type(of: self).allCases.circularElement(after: self)!
}
}
// now the enums need only the protocol conformances, they get the
// functionalities for free
enum CopyState: CaseIterable, InPlaceIterable {
case binary, hex, both
}
You could use Int as raw value for your enum (note that this is also the default raw value if you don't specify it), and use it like this:
enum CopyState: Int {
case binary, hex, both
mutating func next(){
self = CopyState(rawValue: rawValue + 1) ?? .binary
}
}
var state = CopyState.hex
state.next()
print(state) // both
state.next()
print(state) // binary
This works fine as long as you have the raw values of the enum cases in consecutive order. By default the compiler assigns consecutive raw values.
You'd also need to keep in mind to update the next() method if the first case changes, otherwise it will no longer correctly work.
An alternative to the above limitation, suggested by #MartinR, is to force unwrap the raw value zero:
mutating func next(){
self = CopyState(rawValue: rawValue + 1) ?? CopyState(rawValue: 0)!
}
The above code won't require updating the method when the first enum case changes, however it has the potential of crashing the app if the starting raw value of the enum changes.
Swift doc says
When you’re working with enumerations that store integer or string raw
values, you don’t have to explicitly assign a raw value for each case.
When you don’t, Swift automatically assigns the values for you.
For example, when integers are used for raw values, the implicit value
for each case is one more than the previous case. If the first case
doesn’t have a value set, its value is 0.
So this is safe (Swift5)
enum CopyState: Int {
case binary, hex, both
mutating func next(){
self = CopyState(rawValue: rawValue + 1) ?? CopyState(rawValue: 0)!
}
}
If someone is interested in both previous() and next() cases and more generic cyclic offset function like advanced(by n: Int):
extension CaseIterable where Self: Equatable {
func previous() -> Self {
let all = Self.allCases
var idx = all.firstIndex(of: self)!
if idx == all.startIndex {
let lastIndex = all.index(all.endIndex, offsetBy: -1)
return all[lastIndex]
} else {
all.formIndex(&idx, offsetBy: -1)
return all[idx]
}
}
func next() -> Self {
let all = Self.allCases
let idx = all.firstIndex(of: self)!
let next = all.index(after: idx)
return all[next == all.endIndex ? all.startIndex : next]
}
func advanced(by n: Int) -> Self {
let all = Array(Self.allCases)
let idx = (all.firstIndex(of: self)! + n) % all.count
if idx >= 0 {
return all[idx]
} else {
return all[all.count + idx]
}
}
}
Usage:
let s = CopyState.hex.advanced(by: -4)
print(s) // binary
2020
Just FTR here's #Cristik awesome answer, latest syntax:
enum Fruits: CaseIterable {
case apple, banana, pitahaya, cherry
mutating func loopme() {
let a = type(of: self).allCases
self = a[(a.firstIndex(of: self)! + 1) % a.count]
}
}
I would not rely on CaseIterable here. CaseIterable only states to return a collection of all enum values and does not make any guarantee about the order.
The fact, that it does return the cases in the coded order is an implementation detail and may change w/o breaking Protocol conformance.
However, I would assign int values to the cases explicitly:
Your code states that you want an order.
You help your team mates to not just change the order of implicitly assigned cases and break your next() logic.
Closest is #Cristik 's Int backed enum.
enum CopyState: Int {
case binary = 0
case hex = 1
case both = 2
mutating func next() {
self = CopyState(rawValue: rawValue + 1) ?? .binary // or what ever should be the default
}
}
What you've got here is a "circular case sequence". You can make that! 😺
By doing so, you can start with just this, as you had…
enum CopyState {
case binary, hex, both
init() { self = .both }
}
…and be able to do stuff like this:
var state = CopyState()
state.next() // binary
state.offset(by: -2) // hex
CopyState.allCases.elementsEqual( CopyState().prefix(3) ) // true
In reverse order of how you'd write the required pieces:
Adopt the protocol.
extension CopyState: CircularCaseSequence { }
Declare the protocol.
public protocol CircularCaseSequence:
CaseIterable, Sequence, IteratorProtocol, Equatable
{ }
Note the CaseIterable there. Even if CopyState is RawRepresentable, as shown in other answers, it should still be CaseIterable.
Conform to Sequence.
public extension CircularCaseSequence {
mutating func next() -> Self? {
self = offset(by: 1)
return self
}
}
Allow cases to be offset.
public extension CaseIterable where Self: Equatable {
/// Another case from `allCases`.
///
/// Circularly wraps `offset` to always provide an element,
/// even when the resulting `index` is not valid.
func offset(by offset: Int) -> Self {
Self.allCases[self, moduloOffset: offset]!
}
}
Allow Collection elements to be offset.
public extension Collection where Element: Equatable {
/// Circularly wraps `index`, to always provide an element,
/// even when `index` is not valid.
subscript(
_ element: Element,
moduloOffset offset: Int
) -> Element? {
firstIndex(of: element).map {
self[modulo: index($0, offsetBy: offset)]
}
}
}
Allow Collection indices to be wrapped.
public extension Collection {
/// Circularly wraps `index`, to always provide an element,
/// even when `index` is not valid.
subscript(modulo index: Index) -> Element {
self[
self.index(
startIndex,
offsetBy:
distance(from: startIndex, to: index)
.modulo(count)
)
]
}
}
Define modulo.
public extension BinaryInteger {
func modulo(_ divisor: Self) -> Self {
let remainder = self % divisor
return
remainder >= 0
? remainder
: remainder + divisor
}
}
Something I sometimes do is create a simple dictionary like this:
let copyStateDictionary = [
CopyState.binary: CopyState.hex,
CopyState.hex: CopyState.both,
CopyState.both: CopyState.binary
]
Then you can "increment" your variable with:
state = copyStateDictionary[state]
There might be a programmatic way of generating this dictionary, rather than hard-coding it, but if it's just 3-4 values, hard-coding is OK.
How can I determine the number of cases in a Swift enum?
(I would like to avoid manually enumerating through all the values, or using the old "enum_count trick" if possible.)
As of Swift 4.2 (Xcode 10) you can declare
conformance to the CaseIterable protocol, this works for all
enumerations without associated values:
enum Stuff: CaseIterable {
case first
case second
case third
case forth
}
The number of cases is now simply obtained with
print(Stuff.allCases.count) // 4
For more information, see
SE-0194 Derived Collection of Enum Cases
I have a blog post that goes into more detail on this, but as long as your enum's raw type is an integer, you can add a count this way:
enum Reindeer: Int {
case Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner, Blitzen
case Rudolph
static let count: Int = {
var max: Int = 0
while let _ = Reindeer(rawValue: max) { max += 1 }
return max
}()
}
Xcode 10 update
Adopt the CaseIterable protocol in the enum, it provides a static allCases property which contains all enum cases as a Collection . Just use of its count property to know how many cases the enum has.
See Martin's answer for an example (and upvote his answers rather than mine)
Warning: the method below doesn't seem to work anymore.
I'm not aware of any generic method to count the number of enum cases. I've noticed however that the hashValue property of the enum cases is incremental, starting from zero, and with the order determined by the order in which the cases are declared. So, the hash of the last enum plus one corresponds to the number of cases.
For example with this enum:
enum Test {
case ONE
case TWO
case THREE
case FOUR
static var count: Int { return Test.FOUR.hashValue + 1}
}
count returns 4.
I cannot say if that's a rule or if it will ever change in the future, so use at your own risk :)
I define a reusable protocol which automatically performs the case count based on the approach posted by Nate Cook.
protocol CaseCountable {
static var caseCount: Int { get }
}
extension CaseCountable where Self: RawRepresentable, Self.RawValue == Int {
internal static var caseCount: Int {
var count = 0
while let _ = Self(rawValue: count) {
count += 1
}
return count
}
}
Then I can reuse this protocol for example as follows:
enum Planet : Int, CaseCountable {
case Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
}
//..
print(Planet.caseCount)
Create static allValues array as shown in this answer
enum ProductCategory : String {
case Washers = "washers", Dryers = "dryers", Toasters = "toasters"
static let allValues = [Washers, Dryers, Toasters]
}
...
let count = ProductCategory.allValues.count
This is also helpful when you want to enumerate the values, and works for all Enum types
If the implementation doesn't have anything against using integer enums, you could add an extra member value called Count to represent the number of members in the enum - see example below:
enum TableViewSections : Int {
case Watchlist
case AddButton
case Count
}
Now you can get the number of members in the enum by calling, TableViewSections.Count.rawValue which will return 2 for the example above.
When you're handling the enum in a switch statement, make sure to throw an assertion failure when encountering the Count member where you don't expect it:
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let currentSection: TableViewSections = TableViewSections.init(rawValue:section)!
switch(currentSection) {
case .Watchlist:
return watchlist.count
case .AddButton:
return 1
case .Count:
assert(false, "Invalid table view section!")
}
}
This kind of function is able to return the count of your enum.
Swift 2:
func enumCount<T: Hashable>(_: T.Type) -> Int {
var i = 1
while (withUnsafePointer(&i) { UnsafePointer<T>($0).memory }).hashValue != 0 {
i += 1
}
return i
}
Swift 3:
func enumCount<T: Hashable>(_: T.Type) -> Int {
var i = 1
while (withUnsafePointer(to: &i, {
return $0.withMemoryRebound(to: T.self, capacity: 1, { return $0.pointee })
}).hashValue != 0) {
i += 1
}
return i
}
String Enum with Index
enum eEventTabType : String {
case Search = "SEARCH"
case Inbox = "INBOX"
case Accepted = "ACCEPTED"
case Saved = "SAVED"
case Declined = "DECLINED"
case Organized = "ORGANIZED"
static let allValues = [Search, Inbox, Accepted, Saved, Declined, Organized]
var index : Int {
return eEventTabType.allValues.indexOf(self)!
}
}
count : eEventTabType.allValues.count
index : objeEventTabType.index
Enjoy :)
Oh hey everybody, what about unit tests?
func testEnumCountIsEqualToNumberOfItemsInEnum() {
var max: Int = 0
while let _ = Test(rawValue: max) { max += 1 }
XCTAssert(max == Test.count)
}
This combined with Antonio's solution:
enum Test {
case one
case two
case three
case four
static var count: Int { return Test.four.hashValue + 1}
}
in the main code gives you O(1) plus you get a failing test if someone adds an enum case five and doesn't update the implementation of count.
This function relies on 2 undocumented current(Swift 1.1) enum behavior:
Memory layout of enum is just a index of case. If case count is from 2 to 256, it's UInt8.
If the enum was bit-casted from invalid case index, its hashValue is 0
So use at your own risk :)
func enumCaseCount<T:Hashable>(t:T.Type) -> Int {
switch sizeof(t) {
case 0:
return 1
case 1:
for i in 2..<256 {
if unsafeBitCast(UInt8(i), t).hashValue == 0 {
return i
}
}
return 256
case 2:
for i in 257..<65536 {
if unsafeBitCast(UInt16(i), t).hashValue == 0 {
return i
}
}
return 65536
default:
fatalError("too many")
}
}
Usage:
enum Foo:String {
case C000 = "foo"
case C001 = "bar"
case C002 = "baz"
}
enumCaseCount(Foo) // -> 3
I wrote a simple extension which gives all enums where raw value is integer a count property:
extension RawRepresentable where RawValue: IntegerType {
static var count: Int {
var i: RawValue = 0
while let _ = Self(rawValue: i) {
i = i.successor()
}
return Int(i.toIntMax())
}
}
Unfortunately it gives the count property to OptionSetType where it won't work properly, so here is another version which requires explicit conformance to CaseCountable protocol for any enum which cases you want to count:
protocol CaseCountable: RawRepresentable {}
extension CaseCountable where RawValue: IntegerType {
static var count: Int {
var i: RawValue = 0
while let _ = Self(rawValue: i) {
i = i.successor()
}
return Int(i.toIntMax())
}
}
It's very similar to the approach posted by Tom Pelaia, but works with all integer types.
enum EnumNameType: Int {
case first
case second
case third
static var count: Int { return EnumNameType.third.rawValue + 1 }
}
print(EnumNameType.count) //3
OR
enum EnumNameType: Int {
case first
case second
case third
case count
}
print(EnumNameType.count.rawValue) //3
*On Swift 4.2 (Xcode 10) can use:
enum EnumNameType: CaseIterable {
case first
case second
case third
}
print(EnumNameType.allCases.count) //3
Of course, it's not dynamic but for many uses you can get by with a static var added to your Enum
static var count: Int{ return 7 }
and then use it as EnumName.count
For my use case, in a codebase where multiple people could be adding keys to an enum, and these cases should all be available in the allKeys property, it's important that allKeys be validated against the keys in the enum. This is to avoid someone forgetting to add their key to the all keys list. Matching the count of the allKeys array(first created as a set to avoid dupes) against the number of keys in the enum ensures that they are all present.
Some of the answers above show the way to achieve this in Swift 2 but none work in Swift 3. Here is the Swift 3 formatted version:
static func enumCount<T: Hashable>(_ t: T.Type) -> Int {
var i = 1
while (withUnsafePointer(to: &i) {
$0.withMemoryRebound(to:t.self, capacity:1) { $0.pointee.hashValue != 0 }
}) {
i += 1
}
return i
}
static var allKeys: [YourEnumTypeHere] {
var enumSize = enumCount(YourEnumTypeHere.self)
let keys: Set<YourEnumTypeHere> = [.all, .your, .cases, .here]
guard keys.count == enumSize else {
fatalError("Missmatch between allKeys(\(keys.count)) and actual keys(\(enumSize)) in enum.")
}
return Array(keys)
}
Depending on your use case, you might want to just run the test in development to avoid the overhead of using allKeys on each request
Why do you make it all so complex? The SIMPLEST counter of Int enum is to add:
case Count
In the end. And... viola - now you have the count - fast and simple
enum WeekDays : String , CaseIterable
{
case monday = "Mon"
case tuesday = "Tue"
case wednesday = "Wed"
case thursday = "Thu"
case friday = "Fri"
case saturday = "Sat"
case sunday = "Sun"
}
var weekdays = WeekDays.AllCases()
print("\(weekdays.count)")
If you don't want to base your code in the last enum you can create this function inside your enum.
func getNumberOfItems() -> Int {
var i:Int = 0
var exit:Bool = false
while !exit {
if let menuIndex = MenuIndex(rawValue: i) {
i++
}else{
exit = true
}
}
return i
}
A Swift 3 version working with Int type enums:
protocol CaseCountable: RawRepresentable {}
extension CaseCountable where RawValue == Int {
static var count: RawValue {
var i: RawValue = 0
while let _ = Self(rawValue: i) { i += 1 }
return i
}
}
Credits: Based on the answers by bzz and Nate Cook.
Generic IntegerType (in Swift 3 renamed to Integer) is not supported, as it's a heavily fragmented generic type which lacks a lot of functions. successor is not available with Swift 3 anymore.
Be aware that the comment from Code Commander to Nate Cooks answer is still valid:
While nice because you don't need to hardcode a value, this will
instantiate every enum value each time it is called. That is O(n)
instead of O(1).
As far as I know there is currently no workaround when using this as protocol extension (and not implementing in each enum like Nate Cook did) due to static stored properties not being supported in generic types.
Anyway, for small enums this should be no issue. A typical use case would be the section.count for UITableViews as already mentioned by Zorayr.
Extending Matthieu Riegler answer, this is a solution for Swift 3 that doesn't require the use of generics, and can be easily called using the enum type with EnumType.elementsCount:
extension RawRepresentable where Self: Hashable {
// Returns the number of elements in a RawRepresentable data structure
static var elementsCount: Int {
var i = 1
while (withUnsafePointer(to: &i, {
return $0.withMemoryRebound(to: self, capacity: 1, { return
$0.pointee })
}).hashValue != 0) {
i += 1
}
return i
}
I solved this problem for myself by creating a protocol (EnumIntArray) and a global utility function (enumIntArray) that make it very easy to add an "All" variable to any enum (using swift 1.2). The "all" variable will contain an array of all elements in the enum so you can use all.count for the count
It only works with enums that use raw values of type Int but perhaps it can provide some inspiration for other types.
It also addresses the "gap in numbering" and "excessive time to iterate" issues I've read above and elsewhere.
The idea is to add the EnumIntArray protocol to your enum and then define an "all" static variable by calling the enumIntArray function and provide it with the first element (and the last if there are gaps in the numbering).
Because the static variable is only initialized once, the overhead of going through all raw values only hits your program once.
example (without gaps) :
enum Animals:Int, EnumIntArray
{
case Cat=1, Dog, Rabbit, Chicken, Cow
static var all = enumIntArray(Animals.Cat)
}
example (with gaps) :
enum Animals:Int, EnumIntArray
{
case Cat = 1, Dog,
case Rabbit = 10, Chicken, Cow
static var all = enumIntArray(Animals.Cat, Animals.Cow)
}
Here's the code that implements it:
protocol EnumIntArray
{
init?(rawValue:Int)
var rawValue:Int { get }
}
func enumIntArray<T:EnumIntArray>(firstValue:T, _ lastValue:T? = nil) -> [T]
{
var result:[T] = []
var rawValue = firstValue.rawValue
while true
{
if let enumValue = T(rawValue:rawValue++)
{ result.append(enumValue) }
else if lastValue == nil
{ break }
if lastValue != nil
&& rawValue > lastValue!.rawValue
{ break }
}
return result
}
Or you can just define the _count outside the enum, and attach it statically:
let _count: Int = {
var max: Int = 0
while let _ = EnumName(rawValue: max) { max += 1 }
return max
}()
enum EnumName: Int {
case val0 = 0
case val1
static let count = _count
}
That way no matter how many enums you create, it'll only ever be created once.
(delete this answer if static does that)
The following method comes from CoreKit and is similar to the answers some others have suggested. This works with Swift 4.
public protocol EnumCollection: Hashable {
static func cases() -> AnySequence<Self>
static var allValues: [Self] { get }
}
public extension EnumCollection {
public static func cases() -> AnySequence<Self> {
return AnySequence { () -> AnyIterator<Self> in
var raw = 0
return AnyIterator {
let current: Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: self, capacity: 1) { $0.pointee } }
guard current.hashValue == raw else {
return nil
}
raw += 1
return current
}
}
}
public static var allValues: [Self] {
return Array(self.cases())
}
}
enum Weekdays: String, EnumCollection {
case sunday, monday, tuesday, wednesday, thursday, friday, saturday
}
Then you just need to just call Weekdays.allValues.count.
Just want to share a solution when you have an enum with associated values.
enum SomeEnum {
case one
case two(String)
case three(String, Int)
}
CaseIterable doesn't provide allCases automatically.
We can't provide a raw type like Int for your enum to calculate cases count somehow.
What we can do is to use power of switch and fallthrough keyword.
extension SomeEnum {
static var casesCount: Int {
var sum = 0
switch Self.one { // Potential problem
case one:
sum += 1
fallthrough
case two:
sum += 1
fallthrough
case three:
sum += 1
}
return sum
}
}
So now you can say SomeEnum.casesCount.
Remarks:
We still have a problem with switch Self.one {..., we hardcoded the first case. You can easily hack this solution. But I used it just for unit tests so that was not a problem.
If you often need to get cases count in enums with associated values, think about code generation.
struct HashableSequence<T: Hashable>: SequenceType {
func generate() -> AnyGenerator<T> {
var i = 0
return AnyGenerator {
let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
if next.hashValue == i {
i += 1
return next
}
return nil
}
}
}
extension Hashable {
static func enumCases() -> Array<Self> {
return Array(HashableSequence())
}
static var enumCount: Int {
return enumCases().enumCount
}
}
enum E {
case A
case B
case C
}
E.enumCases() // [A, B, C]
E.enumCount // 3
but be careful with usage on non-enum types. Some workaround could be:
struct HashableSequence<T: Hashable>: SequenceType {
func generate() -> AnyGenerator<T> {
var i = 0
return AnyGenerator {
guard sizeof(T) == 1 else {
return nil
}
let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
if next.hashValue == i {
i += 1
return next
}
return nil
}
}
}
extension Hashable {
static func enumCases() -> Array<Self> {
return Array(HashableSequence())
}
static var enumCount: Int {
return enumCases().count
}
}
enum E {
case A
case B
case C
}
Bool.enumCases() // [false, true]
Bool.enumCount // 2
String.enumCases() // []
String.enumCount // 0
Int.enumCases() // []
Int.enumCount // 0
E.enumCases() // [A, B, C]
E.enumCount // 4
It can use a static constant which contains the last value of the enumeration plus one.
enum Color : Int {
case Red, Orange, Yellow, Green, Cyan, Blue, Purple
static let count: Int = Color.Purple.rawValue + 1
func toUIColor() -> UIColor{
switch self {
case .Red:
return UIColor.redColor()
case .Orange:
return UIColor.orangeColor()
case .Yellow:
return UIColor.yellowColor()
case .Green:
return UIColor.greenColor()
case .Cyan:
return UIColor.cyanColor()
case .Blue:
return UIColor.blueColor()
case .Purple:
return UIColor.redColor()
}
}
}
This is minor, but I think a better O(1) solution would be the following (ONLY if your enum is Int starting at x, etc.):
enum Test : Int {
case ONE = 1
case TWO
case THREE
case FOUR // if you later need to add additional enums add above COUNT so COUNT is always the last enum value
case COUNT
static var count: Int { return Test.COUNT.rawValue } // note if your enum starts at 0, some other number, etc. you'll need to add on to the raw value the differential
}
The current selected answer I still believe is the best answer for all enums, unless you are working with Int then I recommend this solution.
How can I determine the number of cases in a Swift enum?
(I would like to avoid manually enumerating through all the values, or using the old "enum_count trick" if possible.)
As of Swift 4.2 (Xcode 10) you can declare
conformance to the CaseIterable protocol, this works for all
enumerations without associated values:
enum Stuff: CaseIterable {
case first
case second
case third
case forth
}
The number of cases is now simply obtained with
print(Stuff.allCases.count) // 4
For more information, see
SE-0194 Derived Collection of Enum Cases
I have a blog post that goes into more detail on this, but as long as your enum's raw type is an integer, you can add a count this way:
enum Reindeer: Int {
case Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner, Blitzen
case Rudolph
static let count: Int = {
var max: Int = 0
while let _ = Reindeer(rawValue: max) { max += 1 }
return max
}()
}
Xcode 10 update
Adopt the CaseIterable protocol in the enum, it provides a static allCases property which contains all enum cases as a Collection . Just use of its count property to know how many cases the enum has.
See Martin's answer for an example (and upvote his answers rather than mine)
Warning: the method below doesn't seem to work anymore.
I'm not aware of any generic method to count the number of enum cases. I've noticed however that the hashValue property of the enum cases is incremental, starting from zero, and with the order determined by the order in which the cases are declared. So, the hash of the last enum plus one corresponds to the number of cases.
For example with this enum:
enum Test {
case ONE
case TWO
case THREE
case FOUR
static var count: Int { return Test.FOUR.hashValue + 1}
}
count returns 4.
I cannot say if that's a rule or if it will ever change in the future, so use at your own risk :)
I define a reusable protocol which automatically performs the case count based on the approach posted by Nate Cook.
protocol CaseCountable {
static var caseCount: Int { get }
}
extension CaseCountable where Self: RawRepresentable, Self.RawValue == Int {
internal static var caseCount: Int {
var count = 0
while let _ = Self(rawValue: count) {
count += 1
}
return count
}
}
Then I can reuse this protocol for example as follows:
enum Planet : Int, CaseCountable {
case Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
}
//..
print(Planet.caseCount)
Create static allValues array as shown in this answer
enum ProductCategory : String {
case Washers = "washers", Dryers = "dryers", Toasters = "toasters"
static let allValues = [Washers, Dryers, Toasters]
}
...
let count = ProductCategory.allValues.count
This is also helpful when you want to enumerate the values, and works for all Enum types
If the implementation doesn't have anything against using integer enums, you could add an extra member value called Count to represent the number of members in the enum - see example below:
enum TableViewSections : Int {
case Watchlist
case AddButton
case Count
}
Now you can get the number of members in the enum by calling, TableViewSections.Count.rawValue which will return 2 for the example above.
When you're handling the enum in a switch statement, make sure to throw an assertion failure when encountering the Count member where you don't expect it:
func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
let currentSection: TableViewSections = TableViewSections.init(rawValue:section)!
switch(currentSection) {
case .Watchlist:
return watchlist.count
case .AddButton:
return 1
case .Count:
assert(false, "Invalid table view section!")
}
}
This kind of function is able to return the count of your enum.
Swift 2:
func enumCount<T: Hashable>(_: T.Type) -> Int {
var i = 1
while (withUnsafePointer(&i) { UnsafePointer<T>($0).memory }).hashValue != 0 {
i += 1
}
return i
}
Swift 3:
func enumCount<T: Hashable>(_: T.Type) -> Int {
var i = 1
while (withUnsafePointer(to: &i, {
return $0.withMemoryRebound(to: T.self, capacity: 1, { return $0.pointee })
}).hashValue != 0) {
i += 1
}
return i
}
String Enum with Index
enum eEventTabType : String {
case Search = "SEARCH"
case Inbox = "INBOX"
case Accepted = "ACCEPTED"
case Saved = "SAVED"
case Declined = "DECLINED"
case Organized = "ORGANIZED"
static let allValues = [Search, Inbox, Accepted, Saved, Declined, Organized]
var index : Int {
return eEventTabType.allValues.indexOf(self)!
}
}
count : eEventTabType.allValues.count
index : objeEventTabType.index
Enjoy :)
Oh hey everybody, what about unit tests?
func testEnumCountIsEqualToNumberOfItemsInEnum() {
var max: Int = 0
while let _ = Test(rawValue: max) { max += 1 }
XCTAssert(max == Test.count)
}
This combined with Antonio's solution:
enum Test {
case one
case two
case three
case four
static var count: Int { return Test.four.hashValue + 1}
}
in the main code gives you O(1) plus you get a failing test if someone adds an enum case five and doesn't update the implementation of count.
This function relies on 2 undocumented current(Swift 1.1) enum behavior:
Memory layout of enum is just a index of case. If case count is from 2 to 256, it's UInt8.
If the enum was bit-casted from invalid case index, its hashValue is 0
So use at your own risk :)
func enumCaseCount<T:Hashable>(t:T.Type) -> Int {
switch sizeof(t) {
case 0:
return 1
case 1:
for i in 2..<256 {
if unsafeBitCast(UInt8(i), t).hashValue == 0 {
return i
}
}
return 256
case 2:
for i in 257..<65536 {
if unsafeBitCast(UInt16(i), t).hashValue == 0 {
return i
}
}
return 65536
default:
fatalError("too many")
}
}
Usage:
enum Foo:String {
case C000 = "foo"
case C001 = "bar"
case C002 = "baz"
}
enumCaseCount(Foo) // -> 3
I wrote a simple extension which gives all enums where raw value is integer a count property:
extension RawRepresentable where RawValue: IntegerType {
static var count: Int {
var i: RawValue = 0
while let _ = Self(rawValue: i) {
i = i.successor()
}
return Int(i.toIntMax())
}
}
Unfortunately it gives the count property to OptionSetType where it won't work properly, so here is another version which requires explicit conformance to CaseCountable protocol for any enum which cases you want to count:
protocol CaseCountable: RawRepresentable {}
extension CaseCountable where RawValue: IntegerType {
static var count: Int {
var i: RawValue = 0
while let _ = Self(rawValue: i) {
i = i.successor()
}
return Int(i.toIntMax())
}
}
It's very similar to the approach posted by Tom Pelaia, but works with all integer types.
enum EnumNameType: Int {
case first
case second
case third
static var count: Int { return EnumNameType.third.rawValue + 1 }
}
print(EnumNameType.count) //3
OR
enum EnumNameType: Int {
case first
case second
case third
case count
}
print(EnumNameType.count.rawValue) //3
*On Swift 4.2 (Xcode 10) can use:
enum EnumNameType: CaseIterable {
case first
case second
case third
}
print(EnumNameType.allCases.count) //3
Of course, it's not dynamic but for many uses you can get by with a static var added to your Enum
static var count: Int{ return 7 }
and then use it as EnumName.count
For my use case, in a codebase where multiple people could be adding keys to an enum, and these cases should all be available in the allKeys property, it's important that allKeys be validated against the keys in the enum. This is to avoid someone forgetting to add their key to the all keys list. Matching the count of the allKeys array(first created as a set to avoid dupes) against the number of keys in the enum ensures that they are all present.
Some of the answers above show the way to achieve this in Swift 2 but none work in Swift 3. Here is the Swift 3 formatted version:
static func enumCount<T: Hashable>(_ t: T.Type) -> Int {
var i = 1
while (withUnsafePointer(to: &i) {
$0.withMemoryRebound(to:t.self, capacity:1) { $0.pointee.hashValue != 0 }
}) {
i += 1
}
return i
}
static var allKeys: [YourEnumTypeHere] {
var enumSize = enumCount(YourEnumTypeHere.self)
let keys: Set<YourEnumTypeHere> = [.all, .your, .cases, .here]
guard keys.count == enumSize else {
fatalError("Missmatch between allKeys(\(keys.count)) and actual keys(\(enumSize)) in enum.")
}
return Array(keys)
}
Depending on your use case, you might want to just run the test in development to avoid the overhead of using allKeys on each request
Why do you make it all so complex? The SIMPLEST counter of Int enum is to add:
case Count
In the end. And... viola - now you have the count - fast and simple
enum WeekDays : String , CaseIterable
{
case monday = "Mon"
case tuesday = "Tue"
case wednesday = "Wed"
case thursday = "Thu"
case friday = "Fri"
case saturday = "Sat"
case sunday = "Sun"
}
var weekdays = WeekDays.AllCases()
print("\(weekdays.count)")
If you don't want to base your code in the last enum you can create this function inside your enum.
func getNumberOfItems() -> Int {
var i:Int = 0
var exit:Bool = false
while !exit {
if let menuIndex = MenuIndex(rawValue: i) {
i++
}else{
exit = true
}
}
return i
}
A Swift 3 version working with Int type enums:
protocol CaseCountable: RawRepresentable {}
extension CaseCountable where RawValue == Int {
static var count: RawValue {
var i: RawValue = 0
while let _ = Self(rawValue: i) { i += 1 }
return i
}
}
Credits: Based on the answers by bzz and Nate Cook.
Generic IntegerType (in Swift 3 renamed to Integer) is not supported, as it's a heavily fragmented generic type which lacks a lot of functions. successor is not available with Swift 3 anymore.
Be aware that the comment from Code Commander to Nate Cooks answer is still valid:
While nice because you don't need to hardcode a value, this will
instantiate every enum value each time it is called. That is O(n)
instead of O(1).
As far as I know there is currently no workaround when using this as protocol extension (and not implementing in each enum like Nate Cook did) due to static stored properties not being supported in generic types.
Anyway, for small enums this should be no issue. A typical use case would be the section.count for UITableViews as already mentioned by Zorayr.
Extending Matthieu Riegler answer, this is a solution for Swift 3 that doesn't require the use of generics, and can be easily called using the enum type with EnumType.elementsCount:
extension RawRepresentable where Self: Hashable {
// Returns the number of elements in a RawRepresentable data structure
static var elementsCount: Int {
var i = 1
while (withUnsafePointer(to: &i, {
return $0.withMemoryRebound(to: self, capacity: 1, { return
$0.pointee })
}).hashValue != 0) {
i += 1
}
return i
}
I solved this problem for myself by creating a protocol (EnumIntArray) and a global utility function (enumIntArray) that make it very easy to add an "All" variable to any enum (using swift 1.2). The "all" variable will contain an array of all elements in the enum so you can use all.count for the count
It only works with enums that use raw values of type Int but perhaps it can provide some inspiration for other types.
It also addresses the "gap in numbering" and "excessive time to iterate" issues I've read above and elsewhere.
The idea is to add the EnumIntArray protocol to your enum and then define an "all" static variable by calling the enumIntArray function and provide it with the first element (and the last if there are gaps in the numbering).
Because the static variable is only initialized once, the overhead of going through all raw values only hits your program once.
example (without gaps) :
enum Animals:Int, EnumIntArray
{
case Cat=1, Dog, Rabbit, Chicken, Cow
static var all = enumIntArray(Animals.Cat)
}
example (with gaps) :
enum Animals:Int, EnumIntArray
{
case Cat = 1, Dog,
case Rabbit = 10, Chicken, Cow
static var all = enumIntArray(Animals.Cat, Animals.Cow)
}
Here's the code that implements it:
protocol EnumIntArray
{
init?(rawValue:Int)
var rawValue:Int { get }
}
func enumIntArray<T:EnumIntArray>(firstValue:T, _ lastValue:T? = nil) -> [T]
{
var result:[T] = []
var rawValue = firstValue.rawValue
while true
{
if let enumValue = T(rawValue:rawValue++)
{ result.append(enumValue) }
else if lastValue == nil
{ break }
if lastValue != nil
&& rawValue > lastValue!.rawValue
{ break }
}
return result
}
Or you can just define the _count outside the enum, and attach it statically:
let _count: Int = {
var max: Int = 0
while let _ = EnumName(rawValue: max) { max += 1 }
return max
}()
enum EnumName: Int {
case val0 = 0
case val1
static let count = _count
}
That way no matter how many enums you create, it'll only ever be created once.
(delete this answer if static does that)
The following method comes from CoreKit and is similar to the answers some others have suggested. This works with Swift 4.
public protocol EnumCollection: Hashable {
static func cases() -> AnySequence<Self>
static var allValues: [Self] { get }
}
public extension EnumCollection {
public static func cases() -> AnySequence<Self> {
return AnySequence { () -> AnyIterator<Self> in
var raw = 0
return AnyIterator {
let current: Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: self, capacity: 1) { $0.pointee } }
guard current.hashValue == raw else {
return nil
}
raw += 1
return current
}
}
}
public static var allValues: [Self] {
return Array(self.cases())
}
}
enum Weekdays: String, EnumCollection {
case sunday, monday, tuesday, wednesday, thursday, friday, saturday
}
Then you just need to just call Weekdays.allValues.count.
Just want to share a solution when you have an enum with associated values.
enum SomeEnum {
case one
case two(String)
case three(String, Int)
}
CaseIterable doesn't provide allCases automatically.
We can't provide a raw type like Int for your enum to calculate cases count somehow.
What we can do is to use power of switch and fallthrough keyword.
extension SomeEnum {
static var casesCount: Int {
var sum = 0
switch Self.one { // Potential problem
case one:
sum += 1
fallthrough
case two:
sum += 1
fallthrough
case three:
sum += 1
}
return sum
}
}
So now you can say SomeEnum.casesCount.
Remarks:
We still have a problem with switch Self.one {..., we hardcoded the first case. You can easily hack this solution. But I used it just for unit tests so that was not a problem.
If you often need to get cases count in enums with associated values, think about code generation.
struct HashableSequence<T: Hashable>: SequenceType {
func generate() -> AnyGenerator<T> {
var i = 0
return AnyGenerator {
let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
if next.hashValue == i {
i += 1
return next
}
return nil
}
}
}
extension Hashable {
static func enumCases() -> Array<Self> {
return Array(HashableSequence())
}
static var enumCount: Int {
return enumCases().enumCount
}
}
enum E {
case A
case B
case C
}
E.enumCases() // [A, B, C]
E.enumCount // 3
but be careful with usage on non-enum types. Some workaround could be:
struct HashableSequence<T: Hashable>: SequenceType {
func generate() -> AnyGenerator<T> {
var i = 0
return AnyGenerator {
guard sizeof(T) == 1 else {
return nil
}
let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
if next.hashValue == i {
i += 1
return next
}
return nil
}
}
}
extension Hashable {
static func enumCases() -> Array<Self> {
return Array(HashableSequence())
}
static var enumCount: Int {
return enumCases().count
}
}
enum E {
case A
case B
case C
}
Bool.enumCases() // [false, true]
Bool.enumCount // 2
String.enumCases() // []
String.enumCount // 0
Int.enumCases() // []
Int.enumCount // 0
E.enumCases() // [A, B, C]
E.enumCount // 4
It can use a static constant which contains the last value of the enumeration plus one.
enum Color : Int {
case Red, Orange, Yellow, Green, Cyan, Blue, Purple
static let count: Int = Color.Purple.rawValue + 1
func toUIColor() -> UIColor{
switch self {
case .Red:
return UIColor.redColor()
case .Orange:
return UIColor.orangeColor()
case .Yellow:
return UIColor.yellowColor()
case .Green:
return UIColor.greenColor()
case .Cyan:
return UIColor.cyanColor()
case .Blue:
return UIColor.blueColor()
case .Purple:
return UIColor.redColor()
}
}
}
This is minor, but I think a better O(1) solution would be the following (ONLY if your enum is Int starting at x, etc.):
enum Test : Int {
case ONE = 1
case TWO
case THREE
case FOUR // if you later need to add additional enums add above COUNT so COUNT is always the last enum value
case COUNT
static var count: Int { return Test.COUNT.rawValue } // note if your enum starts at 0, some other number, etc. you'll need to add on to the raw value the differential
}
The current selected answer I still believe is the best answer for all enums, unless you are working with Int then I recommend this solution.
enum Suit: String {
case spades = "♠"
case hearts = "♥"
case diamonds = "♦"
case clubs = "♣"
}
For example, how can I do something like:
for suit in Suit {
// do something with suit
print(suit.rawValue)
}
Resulting example:
♠
♥
♦
♣
This post is relevant here https://www.swift-studies.com/blog/2014/6/10/enumerating-enums-in-swift
Essentially the proposed solution is
enum ProductCategory : String {
case Washers = "washers", Dryers = "dryers", Toasters = "toasters"
static let allValues = [Washers, Dryers, Toasters]
}
for category in ProductCategory.allValues{
//Do something
}
Swift 4.2+
Starting with Swift 4.2 (with Xcode 10), just add protocol conformance to CaseIterable to benefit from allCases. To add this protocol conformance, you simply need to write somewhere:
extension Suit: CaseIterable {}
If the enum is your own, you may specify the conformance directly in the declaration:
enum Suit: String, CaseIterable { case spades = "♠"; case hearts = "♥"; case diamonds = "♦"; case clubs = "♣" }
Then the following code will print all possible values:
Suit.allCases.forEach {
print($0.rawValue)
}
Compatibility with earlier Swift versions (3.x and 4.x)
If you need to support Swift 3.x or 4.0, you may mimic the Swift 4.2 implementation by adding the following code:
#if !swift(>=4.2)
public protocol CaseIterable {
associatedtype AllCases: Collection where AllCases.Element == Self
static var allCases: AllCases { get }
}
extension CaseIterable where Self: Hashable {
static var allCases: [Self] {
return [Self](AnySequence { () -> AnyIterator<Self> in
var raw = 0
var first: Self?
return AnyIterator {
let current = withUnsafeBytes(of: &raw) { $0.load(as: Self.self) }
if raw == 0 {
first = current
} else if current == first {
return nil
}
raw += 1
return current
}
})
}
}
#endif
I made a utility function iterateEnum() for iterating cases for arbitrary enum types.
Here is the example usage:
enum Suit: String {
case Spades = "♠"
case Hearts = "♥"
case Diamonds = "♦"
case Clubs = "♣"
}
for f in iterateEnum(Suit) {
println(f.rawValue)
}
Which outputs:
♠
♥
♦
♣
But, this is only for debug or test purposes: This relies on several undocumented Swift1.1 compiler behaviors, so, use it at your own risk.
Here is the code:
func iterateEnum<T: Hashable>(_: T.Type) -> GeneratorOf<T> {
var cast: (Int -> T)!
switch sizeof(T) {
case 0: return GeneratorOf(GeneratorOfOne(unsafeBitCast((), T.self)))
case 1: cast = { unsafeBitCast(UInt8(truncatingBitPattern: $0), T.self) }
case 2: cast = { unsafeBitCast(UInt16(truncatingBitPattern: $0), T.self) }
case 4: cast = { unsafeBitCast(UInt32(truncatingBitPattern: $0), T.self) }
case 8: cast = { unsafeBitCast(UInt64($0), T.self) }
default: fatalError("cannot be here")
}
var i = 0
return GeneratorOf {
let next = cast(i)
return next.hashValue == i++ ? next : nil
}
}
The underlying idea is:
Memory representation of enum, excluding enums with associated types, is just an index of cases when the count of the cases is 2...256, it's identical to UInt8, when 257...65536, it's UInt16 and so on. So, it can be unsafeBitcast from corresponding unsigned integer types.
.hashValue of enum values is the same as the index of the case.
.hashValue of enum values bitcasted from invalid index is 0.
Revised for Swift2 and implemented casting ideas from #Kametrixom's answer:
func iterateEnum<T: Hashable>(_: T.Type) -> AnyGenerator<T> {
var i = 0
return anyGenerator {
let next = withUnsafePointer(&i) { UnsafePointer<T>($0).memory }
return next.hashValue == i++ ? next : nil
}
}
Revised for Swift3:
func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
var i = 0
return AnyIterator {
let next = withUnsafePointer(to: &i) {
$0.withMemoryRebound(to: T.self, capacity: 1) { $0.pointee }
}
if next.hashValue != i { return nil }
i += 1
return next
}
}
Revised for Swift3.0.1:
func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
var i = 0
return AnyIterator {
let next = withUnsafeBytes(of: &i) { $0.load(as: T.self) }
if next.hashValue != i { return nil }
i += 1
return next
}
}
The other solutions work but they all make assumptions of for example the number of possible ranks and suits, or what the first and last rank may be. True, the layout of a deck of cards probably isn't going to change much in the foreseeable future. In general, however, it's neater to write code which makes as little assumptions as possible. My solution:
I've added a raw type to the Suit enum, so I can use Suit(rawValue:) to access the Suit cases:
enum Suit: Int {
case Spades = 1
case Hearts, Diamonds, Clubs
func simpleDescription() -> String {
switch self {
case .Spades:
return "spades"
case .Hearts:
return "hearts"
case .Diamonds:
return "diamonds"
case .Clubs:
return "clubs"
}
}
func color() -> String {
switch self {
case .Spades:
return "black"
case .Clubs:
return "black"
case .Diamonds:
return "red"
case .Hearts:
return "red"
}
}
}
enum Rank: Int {
case Ace = 1
case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten
case Jack, Queen, King
func simpleDescription() -> String {
switch self {
case .Ace:
return "ace"
case .Jack:
return "jack"
case .Queen:
return "queen"
case .King:
return "king"
default:
return String(self.rawValue)
}
}
}
Below the implementation of Card's createDeck() method. init(rawValue:) is a failable initializer and returns an optional. By unwrapping and checking its value in both while statements, there's no need to assume the number of Rank or Suit cases:
struct Card {
var rank: Rank
var suit: Suit
func simpleDescription() -> String {
return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
}
func createDeck() -> [Card] {
var n = 1
var deck = [Card]()
while let rank = Rank(rawValue: n) {
var m = 1
while let suit = Suit(rawValue: m) {
deck.append(Card(rank: rank, suit: suit))
m += 1
}
n += 1
}
return deck
}
}
Here is how to call the createDeck method:
let card = Card(rank: Rank.Ace, suit: Suit.Clubs)
let deck = card.createDeck()
I stumbled around in the bits and bytes and created an extension that I later found out works very similar to #rintaro's answer. It's used like this:
enum E : EnumCollection {
case A, B, C
}
Array(E.cases()) // [A, B, C]
What's remarkable is that it's usable on any enum without associated values. Note that this doesn't work for enums that have no cases.
As with #rintaro's answer, this code uses the underlying representation of an enum. This representation isn't documented and might change in the future, which would break it. I don't recommend the usage of this in production.
Code (Swift 2.2, Xcode 7.3.1, not working on Xcode 10):
protocol EnumCollection : Hashable {}
extension EnumCollection {
static func cases() -> AnySequence<Self> {
typealias S = Self
return AnySequence { () -> AnyGenerator<S> in
var raw = 0
return AnyGenerator {
let current : Self = withUnsafePointer(&raw) { UnsafePointer($0).memory }
guard current.hashValue == raw else { return nil }
raw += 1
return current
}
}
}
}
Code (Swift 3, Xcode 8.1, not working on Xcode 10):
protocol EnumCollection : Hashable {}
extension EnumCollection {
static func cases() -> AnySequence<Self> {
typealias S = Self
return AnySequence { () -> AnyIterator<S> in
var raw = 0
return AnyIterator {
let current : Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: S.self, capacity: 1) { $0.pointee } }
guard current.hashValue == raw else { return nil }
raw += 1
return current
}
}
}
}
I have no idea why I need typealias, but the compiler complains without it.
You could iterate through an enum by implementing the ForwardIndexType protocol.
The ForwardIndexType protocol requires you to define a successor() function to step through the elements.
enum Rank: Int, ForwardIndexType {
case Ace = 1
case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten
case Jack, Queen, King
// ... other functions
// Option 1 - Figure it out by hand
func successor() -> Rank {
switch self {
case .Ace:
return .Two
case .Two:
return .Three
// ... etc.
default:
return .King
}
}
// Option 2 - Define an operator!
func successor() -> Rank {
return self + 1
}
}
// NOTE: The operator is defined OUTSIDE the class
func + (left: Rank, right: Int) -> Rank {
// I'm using to/from raw here, but again, you can use a case statement
// or whatever else you can think of
return left == .King ? .King : Rank(rawValue: left.rawValue + right)!
}
Iterating over an open or closed range (..< or ...) will internally call the successor() function which allows you to write this:
// Under the covers, successor(Rank.King) and successor(Rank.Ace) are called to establish limits
for r in Rank.Ace...Rank.King {
// Do something useful
}
This problem is now much easier. Here is my Swift 4.2 Solution:
enum Suit: Int, CaseIterable {
case None
case Spade, Heart, Diamond, Club
static let allNonNullCases = Suit.allCases[Spade.rawValue...]
}
enum Rank: Int, CaseIterable {
case Joker
case Two, Three, Four, Five, Six, Seven, Eight
case Nine, Ten, Jack, Queen, King, Ace
static let allNonNullCases = Rank.allCases[Two.rawValue...]
}
func makeDeck(withJoker: Bool = false) -> [Card] {
var deck = [Card]()
for suit in Suit.allNonNullCases {
for rank in Rank.allNonNullCases {
deck.append(Card(suit: suit, rank: rank))
}
}
if withJoker {
deck.append(Card(suit: .None, rank: .Joker))
}
return deck
}
Pre 4.2:
I like this solution which I put together after finding "List comprehension in Swift".
It uses Int raws instead of Strings but it avoids typing twice, it allows customizing the ranges, and doesn't hard code raw values.
This is a Swift 4 version of my original solution but see the 4.2 improvement above:
enum Suit: Int {
case None
case Spade, Heart, Diamond, Club
static let allRawValues = Suit.Spade.rawValue...Suit.Club.rawValue
static let allCases = Array(allRawValues.map{ Suit(rawValue: $0)! })
}
enum Rank: Int {
case Joker
case Two, Three, Four, Five, Six
case Seven, Eight, Nine, Ten
case Jack, Queen, King, Ace
static let allRawValues = Rank.Two.rawValue...Rank.Ace.rawValue
static let allCases = Array(allRawValues.map{ Rank(rawValue: $0)! })
}
func makeDeck(withJoker: Bool = false) -> [Card] {
var deck = [Card]()
for suit in Suit.allCases {
for rank in Rank.allCases {
deck.append(Card(suit: suit, rank: rank))
}
}
if withJoker {
deck.append(Card(suit: .None, rank: .Joker))
}
return deck
}
In principle it is possible to do it this way assuming that you don't use raw values assignment for enum's cases:
enum RankEnum: Int {
case Ace
case One
case Two
}
class RankEnumGenerator: Generator {
var i = 0
typealias Element = RankEnum
func next() -> Element? {
let r = RankEnum.fromRaw(i)
i += 1
return r
}
}
extension RankEnum {
static func enumerate() -> SequenceOf<RankEnum> {
return SequenceOf<RankEnum>({ RankEnumGenerator() })
}
}
for r in RankEnum.enumerate() {
println("\(r.toRaw())")
}
If you give the enum a raw Int value it will make looping much easier.
For example, you can use anyGenerator to get a generator that can enumerate across your values:
enum Suit: Int, CustomStringConvertible {
case Spades, Hearts, Diamonds, Clubs
var description: String {
switch self {
case .Spades: return "Spades"
case .Hearts: return "Hearts"
case .Diamonds: return "Diamonds"
case .Clubs: return "Clubs"
}
}
static func enumerate() -> AnyGenerator<Suit> {
var nextIndex = Spades.rawValue
return anyGenerator { Suit(rawValue: nextIndex++) }
}
}
// You can now use it like this:
for suit in Suit.enumerate() {
suit.description
}
// or like this:
let allSuits: [Suit] = Array(Suit.enumerate())
However, this looks like a fairly common pattern, wouldn't it be nice if we could make any enum type enumerable by simply conforming to a protocol? Well with Swift 2.0 and protocol extensions, now we can!
Simply add this to your project:
protocol EnumerableEnum {
init?(rawValue: Int)
static func firstValue() -> Int
}
extension EnumerableEnum {
static func enumerate() -> AnyGenerator<Self> {
var nextIndex = firstRawValue()
return anyGenerator { Self(rawValue: nextIndex++) }
}
static func firstRawValue() -> Int { return 0 }
}
Now any time you create an enum (so long as it has an Int raw value), you can make it enumerable by conforming to the protocol:
enum Rank: Int, EnumerableEnum {
case Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King
}
// ...
for rank in Rank.enumerate() { ... }
If your enum values don't start with 0 (the default), override the firstRawValue method:
enum DeckColor: Int, EnumerableEnum {
case Red = 10, Blue, Black
static func firstRawValue() -> Int { return Red.rawValue }
}
// ...
let colors = Array(DeckColor.enumerate())
The final Suit class, including replacing simpleDescription with the more standard CustomStringConvertible protocol, will look like this:
enum Suit: Int, CustomStringConvertible, EnumerableEnum {
case Spades, Hearts, Diamonds, Clubs
var description: String {
switch self {
case .Spades: return "Spades"
case .Hearts: return "Hearts"
case .Diamonds: return "Diamonds"
case .Clubs: return "Clubs"
}
}
}
// ...
for suit in Suit.enumerate() {
print(suit.description)
}
Swift 3 syntax:
protocol EnumerableEnum {
init?(rawValue: Int)
static func firstRawValue() -> Int
}
extension EnumerableEnum {
static func enumerate() -> AnyIterator<Self> {
var nextIndex = firstRawValue()
let iterator: AnyIterator<Self> = AnyIterator {
defer { nextIndex = nextIndex + 1 }
return Self(rawValue: nextIndex)
}
return iterator
}
static func firstRawValue() -> Int {
return 0
}
}
Updated Code : Swift 4.2/Swift 5
enum Suit: String, CaseIterable {
case spades = "♠"
case hearts = "♥"
case diamonds = "♦"
case clubs = "♣"
}
To access the Output as per question:
for suitKey in Suit.allCases {
print(suitKey.rawValue)
}
Output :
♠
♥
♦
♣
CaseIterable: provides a collection of all of its values.
Types that conform to the CaseIterable protocol are typically enumerations without associated values. When using a CaseIterable type, you can access a collection of all of the type’s cases by using the type’s allCases property.
For accessing cases we are using .allCases. For more information click https://developer.apple.com/documentation/swift/caseiterable
Updated to Swift 2.2+
func iterateEnum<T: Hashable>(_: T.Type) -> AnyGenerator<T> {
var i = 0
return AnyGenerator {
let next = withUnsafePointer(&i) {
UnsafePointer<T>($0).memory
}
if next.hashValue == i {
i += 1
return next
} else {
return nil
}
}
}
It's updated code to Swift 2.2 form #Kametrixom's answer
For Swift 3.0+ (many thanks to #Philip)
func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
var i = 0
return AnyIterator {
let next = withUnsafePointer(&i) {
UnsafePointer<T>($0).pointee
}
if next.hashValue == i {
i += 1
return next
} else {
return nil
}
}
}
Swift 5 Solution:
enum Suit: String, CaseIterable {
case spades = "♠"
case hearts = "♥"
case diamonds = "♦"
case clubs = "♣"
}
// access cases like this:
for suitKey in Suit.allCases {
print(suitKey)
}
Xcode 10 with Swift 4.2
enum Filter: String, CaseIterable {
case salary = "Salary"
case experience = "Experience"
case technology = "Technology"
case unutilized = "Unutilized"
case unutilizedHV = "Unutilized High Value"
static let allValues = Filter.allCases.map { $0.rawValue }
}
Call it
print(Filter.allValues)
Prints:
["Salary", "Experience", "Technology", "Unutilized", "Unutilized High Value"]
Older versions
For enum representing Int
enum Filter: Int {
case salary
case experience
case technology
case unutilized
case unutilizedHV
static let allRawValues = salary.rawValue...unutilizedHV.rawValue // First to last case
static let allValues = allRawValues.map { Filter(rawValue: $0)!.rawValue }
}
Call it like this:
print(Filter.allValues)
Prints:
[0, 1, 2, 3, 4]
For enum representing String
enum Filter: Int {
case salary
case experience
case technology
case unutilized
case unutilizedHV
static let allRawValues = salary.rawValue...unutilizedHV.rawValue // First to last case
static let allValues = allRawValues.map { Filter(rawValue: $0)!.description }
}
extension Filter: CustomStringConvertible {
var description: String {
switch self {
case .salary: return "Salary"
case .experience: return "Experience"
case .technology: return "Technology"
case .unutilized: return "Unutilized"
case .unutilizedHV: return "Unutilized High Value"
}
}
}
Call it
print(Filter.allValues)
Prints:
["Salary", "Experience", "Technology", "Unutilized", "Unutilized High Value"]
I found myself doing .allValues alot throughout my code. I finally figured out a way to simply conform to an Iteratable protocol and have an rawValues() method.
protocol Iteratable {}
extension RawRepresentable where Self: RawRepresentable {
static func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
var i = 0
return AnyIterator {
let next = withUnsafePointer(to: &i) {
$0.withMemoryRebound(to: T.self, capacity: 1) { $0.pointee }
}
if next.hashValue != i { return nil }
i += 1
return next
}
}
}
extension Iteratable where Self: RawRepresentable, Self: Hashable {
static func hashValues() -> AnyIterator<Self> {
return iterateEnum(self)
}
static func rawValues() -> [Self.RawValue] {
return hashValues().map({$0.rawValue})
}
}
// Example
enum Grocery: String, Iteratable {
case Kroger = "kroger"
case HEB = "h.e.b."
case Randalls = "randalls"
}
let groceryHashes = Grocery.hashValues() // AnyIterator<Grocery>
let groceryRawValues = Grocery.rawValues() // ["kroger", "h.e.b.", "randalls"]
EDIT:
Swift Evolution Proposal SE-0194 Derived Collection of Enum Cases proposes a level headed solution to this problem. We see it in Swift 4.2 and newer. The proposal also points out to some workarounds that are similar to some already mentioned here but it might be interesting to see nevertheless.
I will also keep my original post for completeness' sake.
This is yet another approach based on #Peymmankh's answer, adapted to Swift 3.
public protocol EnumCollection: Hashable {}
extension EnumCollection {
public static func allValues() -> [Self] {
typealias S = Self
let retVal = AnySequence { () -> AnyIterator<S> in
var raw = 0
return AnyIterator {
let current = withUnsafePointer(to: &raw) {
$0.withMemoryRebound(to: S.self, capacity: 1) { $0.pointee }
}
guard current.hashValue == raw else { return nil }
raw += 1
return current
}
}
return [S](retVal)
}
enum Rank: Int {
...
static let ranks = (Rank.Ace.rawValue ... Rank.King.rawValue).map{Rank(rawValue: $0)! }
}
enum Suit {
...
static let suits = [Spades, Hearts, Diamonds, Clubs]
}
struct Card {
...
static func fullDesk() -> [Card] {
var desk: [Card] = []
for suit in Suit.suits {
for rank in Rank.ranks {
desk.append(Card(rank: rank,suit: suit))
}
}
return desk
}
}
How about this?
You can try to enumerate like this
enum Planet: String {
case Mercury
case Venus
case Earth
case Mars
static var enumerate: [Planet] {
var a: [Planet] = []
switch Planet.Mercury {
case .Mercury: a.append(.Mercury); fallthrough
case .Venus: a.append(.Venus); fallthrough
case .Earth: a.append(.Earth); fallthrough
case .Mars: a.append(.Mars)
}
return a
}
}
Planet.enumerate // [Mercury, Venus, Earth, Mars]
In Swift 3, when the underlying enum has rawValue, you could implement the Strideable protocol. The advantages are that no arrays of values are created like in some other suggestions and that the standard Swift "for in" loop works, which makes a nice syntax.
// "Int" to get rawValue, and Strideable so we can iterate
enum MyColorEnum: Int, Strideable {
case Red
case Green
case Blue
case Black
// required by Strideable
typealias Stride = Int
func advanced(by n:Stride) -> MyColorEnum {
var next = self.rawValue + n
if next > MyColorEnum.Black.rawValue {
next = MyColorEnum.Black.rawValue
}
return MyColorEnum(rawValue: next)!
}
func distance(to other: MyColorEnum) -> Int {
return other.rawValue - self.rawValue
}
// just for printing
func simpleDescription() -> String {
switch self {
case .Red: return "Red"
case .Green: return "Green"
case .Blue: return "Blue"
case .Black: return "Black"
}
}
}
// this is how you use it:
for i in MyColorEnum.Red ... MyColorEnum.Black {
print("ENUM: \(i)")
}
This solution strikes the right balance of readability and maintainability.
struct Card {
// ...
static func deck() -> Card[] {
var deck = Card[]()
for rank in Rank.Ace.toRaw()...Rank.King.toRaw() {
for suit in [Suit.Spades, .Hearts, .Clubs, .Diamonds] {
let card = Card(rank: Rank.fromRaw(rank)!, suit: suit)
deck.append(card)
}
}
return deck
}
}
let deck = Card.deck()
Sorry, my answer was specific to how I used this post in what I needed to do. For those who stumble upon this question, looking for a way to find a case within an enum, this is the way to do it (new in Swift 2):
Edit: lowercase camelCase is now the standard for Swift 3 enum values
// From apple docs: If the raw-value type is specified as String and you don’t assign values to the cases explicitly, each unassigned case is implicitly assigned a string with the same text as the name of that case.
enum Theme: String
{
case white, blue, green, lavender, grey
}
func loadTheme(theme: String)
{
// this checks the string against the raw value of each enum case (note that the check could result in a nil value, since it's an optional, which is why we introduce the if/let block
if let testTheme = Theme(rawValue: theme)
{
// testTheme is guaranteed to have an enum value at this point
self.someOtherFunction(testTheme)
}
}
For those wondering about the enumerating on an enum, the answers given on this page that include a static var/let containing an array of all enum values are correct. The latest Apple example code for tvOS contains this exact same technique.
That being said, they should build a more convenient mechanism into the language (Apple, are you listening?)!
The experiment was:
EXPERIMENT
Add a method to Card that creates a full deck of cards, with one card of each combination of rank and suit.
So without modifying or enhancing the given code other than adding the method (and without using stuff that hasn't been taught yet), I came up with this solution:
struct Card {
var rank: Rank
var suit: Suit
func simpleDescription() -> String {
return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
}
func createDeck() -> [Card] {
var deck: [Card] = []
for rank in Rank.Ace.rawValue...Rank.King.rawValue {
for suit in Suit.Spades.rawValue...Suit.Clubs.rawValue {
let card = Card(rank: Rank(rawValue: rank)!, suit: Suit(rawValue: suit)!)
//println(card.simpleDescription())
deck += [card]
}
}
return deck
}
}
let threeOfSpades = Card(rank: .Three, suit: .Spades)
let threeOfSpadesDescription = threeOfSpades.simpleDescription()
let deck = threeOfSpades.createDeck()
Here is a method I use to both iterate an enum and provide multiple values types from one enum
enum IterateEnum: Int {
case Zero
case One
case Two
case Three
case Four
case Five
case Six
case Seven
//tuple allows multiple values to be derived from the enum case, and
//since it is using a switch with no default, if a new case is added,
//a compiler error will be returned if it doesn't have a value tuple set
var value: (french: String, spanish: String, japanese: String) {
switch self {
case .Zero: return (french: "zéro", spanish: "cero", japanese: "nuru")
case .One: return (french: "un", spanish: "uno", japanese: "ichi")
case .Two: return (french: "deux", spanish: "dos", japanese: "ni")
case .Three: return (french: "trois", spanish: "tres", japanese: "san")
case .Four: return (french: "quatre", spanish: "cuatro", japanese: "shi")
case .Five: return (french: "cinq", spanish: "cinco", japanese: "go")
case .Six: return (french: "six", spanish: "seis", japanese: "roku")
case .Seven: return (french: "sept", spanish: "siete", japanese: "shichi")
}
}
//Used to iterate enum or otherwise access enum case by index order.
//Iterate by looping until it returns nil
static func item(index: Int) -> IterateEnum? {
return IterateEnum.init(rawValue: index)
}
static func numberFromSpanish(number: String) -> IterateEnum? {
return findItem { $0.value.spanish == number }
}
//use block to test value property to retrieve the enum case
static func findItem(predicate: ((_: IterateEnum) -> Bool)) -> IterateEnum? {
var enumIndex: Int = -1
var enumCase: IterateEnum?
//Iterate until item returns nil
repeat {
enumIndex += 1
enumCase = IterateEnum.item(index: enumIndex)
if let eCase = enumCase {
if predicate(eCase) {
return eCase
}
}
} while enumCase != nil
return nil
}
}
var enumIndex: Int = -1
var enumCase: IterateEnum?
// Iterate until item returns nil
repeat {
enumIndex += 1
enumCase = IterateEnum.item(index: enumIndex)
if let eCase = enumCase {
print("The number \(eCase) in french: \(eCase.value.french), spanish: \(eCase.value.spanish), japanese: \(eCase.value.japanese)")
}
} while enumCase != nil
print("Total of \(enumIndex) cases")
let number = IterateEnum.numberFromSpanish(number: "siete")
print("siete in japanese: \((number?.value.japanese ?? "Unknown"))")
This is the output:
The number Zero in french: zéro, spanish: cero, japanese: nuru
The number One in french: un, spanish: uno, japanese: ichi
The number Two in french: deux, spanish: dos, japanese: ni
The number Three in french: trois, spanish: tres, japanese: san
The number Four in french: quatre, spanish: cuatro, japanese: shi
The number Five in french: cinq, spanish: cinco, japanese: go
The number Six in french: six, spanish: seis, japanese: roku
The number Seven in french: sept, spanish: siete, japanese: shichi
Total of 8 cases
siete in japanese: shichi
UPDATE
I recently created a protocol to handle the enumeration. The protocol requires an enum with an Int raw value:
protocol EnumIteration {
//Used to iterate enum or otherwise access enum case by index order. Iterate by looping until it returns nil
static func item(index:Int) -> Self?
static func iterate(item:((index:Int, enumCase:Self)->()), completion:(()->())?) {
static func findItem(predicate:((enumCase:Self)->Bool)) -> Self?
static func count() -> Int
}
extension EnumIteration where Self: RawRepresentable, Self.RawValue == Int {
//Used to iterate enum or otherwise access enum case by index order. Iterate by looping until it returns nil
static func item(index:Int) -> Self? {
return Self.init(rawValue: index)
}
static func iterate(item:((index:Int, enumCase:Self)->()), completion:(()->())?) {
var enumIndex:Int = -1
var enumCase:Self?
//Iterate until item returns nil
repeat {
enumIndex += 1
enumCase = Self.item(enumIndex)
if let eCase = enumCase {
item(index: enumIndex, enumCase: eCase)
}
} while enumCase != nil
completion?()
}
static func findItem(predicate:((enumCase:Self)->Bool)) -> Self? {
var enumIndex:Int = -1
var enumCase:Self?
//Iterate until item returns nil
repeat {
enumIndex += 1
enumCase = Self.item(enumIndex)
if let eCase = enumCase {
if predicate(enumCase:eCase) {
return eCase
}
}
} while enumCase != nil
return nil
}
static func count() -> Int {
var enumIndex:Int = -1
var enumCase:Self?
//Iterate until item returns nil
repeat {
enumIndex += 1
enumCase = Self.item(enumIndex)
} while enumCase != nil
//last enumIndex (when enumCase == nil) is equal to the enum count
return enumIndex
}
}
This seems like a hack but if you use raw values you can do something like this
enum Suit: Int {
case Spades = 0, Hearts, Diamonds, Clubs
...
}
var suitIndex = 0
while var suit = Suit.fromRaw(suitIndex++) {
...
}
While dealing with Swift 2.0 here is my suggestion:
I have added the raw type to Suit enum
enum Suit: Int {
then:
struct Card {
var rank: Rank
var suit: Suit
func fullDeck()-> [Card] {
var deck = [Card]()
for i in Rank.Ace.rawValue...Rank.King.rawValue {
for j in Suit.Spades.rawValue...Suit.Clubs.rawValue {
deck.append(Card(rank:Rank(rawValue: i)! , suit: Suit(rawValue: j)!))
}
}
return deck
}
}
As with #Kametrixom answer here I believe returning an array would be better than returning AnySequence, since you can have access to all of Array's goodies such as count, etc.
Here's the re-write:
public protocol EnumCollection : Hashable {}
extension EnumCollection {
public static func allValues() -> [Self] {
typealias S = Self
let retVal = AnySequence { () -> AnyGenerator<S> in
var raw = 0
return AnyGenerator {
let current : Self = withUnsafePointer(&raw) { UnsafePointer($0).memory }
guard current.hashValue == raw else { return nil }
raw += 1
return current
}
}
return [S](retVal)
}
}
Another solution:
enum Suit: String {
case spades = "♠"
case hearts = "♥"
case diamonds = "♦"
case clubs = "♣"
static var count: Int {
return 4
}
init(index: Int) {
switch index {
case 0: self = .spades
case 1: self = .hearts
case 2: self = .diamonds
default: self = .clubs
}
}
}
for i in 0..<Suit.count {
print(Suit(index: i).rawValue)
}
This is a pretty old post, from Swift 2.0. There are now some better solutions here that use newer features of swift 3.0:
Iterating through an Enum in Swift 3.0
And on this question there is a solution that uses a new feature of (the not-yet-released as I write this edit) Swift 4.2:
How do I get the count of a Swift enum?
There are lots of good solutions in this thread and others however some of them are very complicated. I like to simplify as much as possible. Here is a solution which may or may not work for different needs but I think it works well in most cases:
enum Number: String {
case One
case Two
case Three
case Four
case EndIndex
func nextCase () -> Number
{
switch self {
case .One:
return .Two
case .Two:
return .Three
case .Three:
return .Four
case .Four:
return .EndIndex
/*
Add all additional cases above
*/
case .EndIndex:
return .EndIndex
}
}
static var allValues: [String] {
var array: [String] = Array()
var number = Number.One
while number != Number.EndIndex {
array.append(number.rawValue)
number = number.nextCase()
}
return array
}
}
To iterate:
for item in Number.allValues {
print("number is: \(item)")
}
Enums have toRaw() and fromRaw() methods. So if your raw value is an Int, you can iterate from the first to last enum:
enum Suit: Int {
case Spades = 1
case Hearts, Diamonds, Clubs
func simpleDescription() -> String {
switch self {
case .Spades:
return "spades"
case .Hearts:
return "hearts"
case .Diamonds:
return "diamonds"
case .Clubs:
return "clubs"
}
}
}
for i in Suit.Spades.toRaw()...Suit.Clubs.toRaw() {
if let covertedSuit = Suit.fromRaw(i) {
let description = covertedSuit.simpleDescription()
}
}
One gotcha is that you need to test for optional values before running the simpleDescription method, so we set convertedSuit to our value first and then set a constant to convertedSuit.simpleDescription()
Here's my suggested approach. It's not completely satisfactory (I'm very new to Swift and OOP!) but maybe someone can refine it. The idea is to have each enum provide its own range information as .first and .last properties. It adds just two lines of code to each enum: still a bit hard-coded, but at least it's not duplicating the whole set. It does require modifying the Suit enum to be an Int like the Rank enum is, instead of untyped.
Rather than echo the whole solution, here's the code I added to the . enum, somewhere after the case statements (Suit enum is similar):
var first: Int { return Ace.toRaw() }
var last: Int { return King.toRaw() }
and the loop I used to build the deck as an array of String. (The problem definition did not state how the deck was to be structured.)
func createDeck() -> [String] {
var deck: [String] = []
var card: String
for r in Rank.Ace.first...Rank.Ace.last {
for s in Suit.Hearts.first...Suit.Hearts.last {
card = Rank.simpleDescription( Rank.fromRaw(r)!)() + " of " + Suit.simpleDescription( Suit.fromRaw(s)!)()
deck.append( card)
}
}
return deck
}
It's unsatisfactory because the properties are associated to an element rather than to the enum. But it does add clarity to the 'for' loops. I'd like it to say Rank.first instead of Rank.Ace.first. It works (with any element), but it's ugly. Can someone show how to elevate that to the enum level?
And to make it work, I lifted the createDeck method out of the Card struct. I could not figure out how to get a [String] array returned from that struct, and that seems a bad place to put such a method anyway.
I did it using computed property, which returns the array of all values (thanks to this post http://natecook.com/blog/2014/10/loopy-random-enum-ideas/). However, it also uses int raw-values, but I don't need to repeat all members of enumeration in separate property.
UPDATE Xcode 6.1 changed a bit a way how to get enum member using rawValue, so I fixed listing. Also fixed small error with wrong first rawValue.
enum ValidSuits: Int {
case Clubs = 0, Spades, Hearts, Diamonds
func description() -> String {
switch self {
case .Clubs:
return "♣︎"
case .Spades:
return "♠︎"
case .Diamonds:
return "♦︎"
case .Hearts:
return "♥︎"
}
}
static var allSuits: [ValidSuits] {
return Array(
SequenceOf {
() -> GeneratorOf<ValidSuits> in
var i=0
return GeneratorOf<ValidSuits> {
return ValidSuits(rawValue: i++)
}
}
)
}
}