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I a codable serialization extension which I use to turn my Codable struct to dictionaries, the problem I am facing is strings. I get string value from my UITextField at at times this value could be empty and as a result an empty string is decoded. How can I return nil if the value is an empty string.
extension Encodable {
var requestDictionary: [String: Any]? {
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
guard let data = try? encoder.encode(self) else { return nil }
return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
}
}
if I have a Struct
let example = Exa(age: 10, name: "")
let dict = example.requestDictionary
print(dict)
I want it to just print ["age": 10] and return nil for the empty string
You can implement your own String encoding method extending KeyedEncodingContainer:
extension KeyedEncodingContainer {
mutating func encode(_ value: String, forKey key: K) throws {
guard !value.isEmpty else { return }
try encodeIfPresent(value, forKey: key)
}
}
Btw your request dictionary can be simplified as:
extension Encodable {
var dictionary: [String: Any]? {
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
return try? JSONSerialization.jsonObject(with: encoder.encode(self)) as? [String: Any]
}
}
Playground testing:
struct Exa: Encodable {
let age: Int
let name: String
}
let example = Exa(age: 10, name: "")
let dict = example.dictionary!
print(dict) // "["age": 10]\n"
I'll just another approach using a property wrapper to mark which properties could be skipped.
#propertyWrapper
struct SkipEmpty {
var wrappedValue: String
}
extension SkipEmpty: Codable {
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
self.wrappedValue = try container.decode(String.self)
}
func encode(to encoder: Encoder) throws {
// nothing to do here, see below
}
}
But to actually skip, you'd also need to create a overload for the KeyedEncodingContainer.encode method for the SkipEmpty type:
extension KeyedEncodingContainer {
mutating func encode(_ value: SkipEmpty, forKey key: K) throws {
if !value.wrappedValue.isEmpty {
try encode(value.wrappedValue, forKey: key) // encode the value here
}
}
}
You could possibly try to make it more generic, e.g. SkipEmpty<T: Codable> and provide another argument for the value to skip or a predicate, etc...
The usage is:
struct Exa: Encodable {
var age: Int
#SkipEmpty var name: String
}
I'm using this library which has created non-empty collections like arrays, dictionaries and strings. https://github.com/pointfreeco/swift-nonempty
When I decode to the non-empty array I get the following error
Swift.DecodingError.typeMismatch(Swift.Dictionary, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "poiList", intValue: nil)], debugDescription: "Expected to decode Dictionary but found an array instead.", underlyingError: nil))
This is my structure
struct LocationCarModel: Codable {
// MARK: - Properties
var poiList: NonEmptyArray<PointOfInterest>
// MARK: - PointOfInterest
struct PointOfInterest: Codable {
var id: Int
var coordinate: Position
var fleetType: String
let numberPlate = "HCD837EC"
let model: String = "Tesla S"
let fuel: Double = 0.9
}
}
This is the response I'm getting https://fake-poi-api.mytaxi.com/?p2Lat=53.394655&p1Lon=9.757589&p1Lat=53.694865&p2Lon=10.099891
and this how I'm decoding it.
public extension Decodable {
static func parse(from item: Any?, strategy: JSONDecoder.KeyDecodingStrategy = .useDefaultKeys) -> Self? {
guard let data = self.data(from: item) else {
return nil
}
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = strategy
do {
let result = try decoder.decode(Self.self, from: data)
return result
} catch {
debugPrint(error)
return nil
}
}
private static func data(from item: Any?) -> Data? {
switch item {
case let data as Data:
return data
case let string as String:
return string.data(using: .utf8)
case .some(let item):
return try? JSONSerialization.data(withJSONObject: item, options: [])
case nil:
return nil
}
}
}
and the line to decode using the above function is
let model = LocationCarModel.parse(from: data)
Changing poiList to the standard swift array then no error occurs.
Any ideas how I can solve this issue? Any help would be appreciated. Thank you in advance.
You need to have your own init(from:) for the top struct since JSONDecoder doesn't understand NonEmpty and how to initialise it. Apart from the init I also added coding keys and a new error
enum DecodeError: Error {
case arrayIsEmptyError
}
struct LocationCarModel: Codable {
var poiList: NonEmpty<[PointOfInterest]>
enum CodingKeys: String, CodingKey {
case poiList
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let array = try container.decode([PointOfInterest].self, forKey: .poiList)
guard let first = array.first else {
throw DecodeError.arrayIsEmptyError
}
poiList = NonEmptyArray(first, array)
}
//...
}
You can try
struct Root: Codable {
let poiList: [PoiList]
}
// MARK: - PoiList
struct PoiList: Codable {
let id: Int
let coordinate: Coordinate
let fleetType: String
let heading: Double
}
// MARK: - Coordinate
struct Coordinate: Codable {
let latitude, longitude: Double
}
let res = try? JSONDecoder().decode(Root.self,from:data)
print(res)
I have a struct that implements Swift 4’s Codable. Is there a simple built-in way to encode that struct into a dictionary?
let struct = Foo(a: 1, b: 2)
let dict = something(struct)
// now dict is ["a": 1, "b": 2]
If you don't mind a bit of shifting of data around you could use something like this:
extension Encodable {
func asDictionary() throws -> [String: Any] {
let data = try JSONEncoder().encode(self)
guard let dictionary = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any] else {
throw NSError()
}
return dictionary
}
}
Or an optional variant
extension Encodable {
var dictionary: [String: Any]? {
guard let data = try? JSONEncoder().encode(self) else { return nil }
return (try? JSONSerialization.jsonObject(with: data, options: .allowFragments)).flatMap { $0 as? [String: Any] }
}
}
Assuming Foo conforms to Codable or really Encodable then you can do this.
let struct = Foo(a: 1, b: 2)
let dict = try struct.asDictionary()
let optionalDict = struct.dictionary
If you want to go the other way(init(any)), take a look at this Init an object conforming to Codable with a dictionary/array
Here are simple implementations of DictionaryEncoder / DictionaryDecoder that wrap JSONEncoder, JSONDecoder and JSONSerialization, that also handle encoding / decoding strategies…
class DictionaryEncoder {
private let encoder = JSONEncoder()
var dateEncodingStrategy: JSONEncoder.DateEncodingStrategy {
set { encoder.dateEncodingStrategy = newValue }
get { return encoder.dateEncodingStrategy }
}
var dataEncodingStrategy: JSONEncoder.DataEncodingStrategy {
set { encoder.dataEncodingStrategy = newValue }
get { return encoder.dataEncodingStrategy }
}
var nonConformingFloatEncodingStrategy: JSONEncoder.NonConformingFloatEncodingStrategy {
set { encoder.nonConformingFloatEncodingStrategy = newValue }
get { return encoder.nonConformingFloatEncodingStrategy }
}
var keyEncodingStrategy: JSONEncoder.KeyEncodingStrategy {
set { encoder.keyEncodingStrategy = newValue }
get { return encoder.keyEncodingStrategy }
}
func encode<T>(_ value: T) throws -> [String: Any] where T : Encodable {
let data = try encoder.encode(value)
return try JSONSerialization.jsonObject(with: data, options: .allowFragments) as! [String: Any]
}
}
class DictionaryDecoder {
private let decoder = JSONDecoder()
var dateDecodingStrategy: JSONDecoder.DateDecodingStrategy {
set { decoder.dateDecodingStrategy = newValue }
get { return decoder.dateDecodingStrategy }
}
var dataDecodingStrategy: JSONDecoder.DataDecodingStrategy {
set { decoder.dataDecodingStrategy = newValue }
get { return decoder.dataDecodingStrategy }
}
var nonConformingFloatDecodingStrategy: JSONDecoder.NonConformingFloatDecodingStrategy {
set { decoder.nonConformingFloatDecodingStrategy = newValue }
get { return decoder.nonConformingFloatDecodingStrategy }
}
var keyDecodingStrategy: JSONDecoder.KeyDecodingStrategy {
set { decoder.keyDecodingStrategy = newValue }
get { return decoder.keyDecodingStrategy }
}
func decode<T>(_ type: T.Type, from dictionary: [String: Any]) throws -> T where T : Decodable {
let data = try JSONSerialization.data(withJSONObject: dictionary, options: [])
return try decoder.decode(type, from: data)
}
}
Usage is similar to JSONEncoder / JSONDecoder…
let dictionary = try DictionaryEncoder().encode(object)
and
let object = try DictionaryDecoder().decode(Object.self, from: dictionary)
For convenience, I've put this all in a repo… https://github.com/ashleymills/SwiftDictionaryCoding
I have create a library called CodableFirebase and it's initial purpose was to use it with Firebase Database, but it does actually what you need: it creates a dictionary or any other type just like in JSONDecoder but you don't need to do the double conversion here like you do in other answers. So it would look something like:
import CodableFirebase
let model = Foo(a: 1, b: 2)
let dict = try! FirebaseEncoder().encode(model)
There is no built in way to do that.
As answered above if you have no performance issues then you can accept the JSONEncoder + JSONSerialization implementation.
But I would rather go the standard library's way to provide an encoder/decoder object.
class DictionaryEncoder {
private let jsonEncoder = JSONEncoder()
/// Encodes given Encodable value into an array or dictionary
func encode<T>(_ value: T) throws -> Any where T: Encodable {
let jsonData = try jsonEncoder.encode(value)
return try JSONSerialization.jsonObject(with: jsonData, options: .allowFragments)
}
}
class DictionaryDecoder {
private let jsonDecoder = JSONDecoder()
/// Decodes given Decodable type from given array or dictionary
func decode<T>(_ type: T.Type, from json: Any) throws -> T where T: Decodable {
let jsonData = try JSONSerialization.data(withJSONObject: json, options: [])
return try jsonDecoder.decode(type, from: jsonData)
}
}
You can try it with following code:
struct Computer: Codable {
var owner: String?
var cpuCores: Int
var ram: Double
}
let computer = Computer(owner: "5keeve", cpuCores: 8, ram: 4)
let dictionary = try! DictionaryEncoder().encode(computer)
let decodedComputer = try! DictionaryDecoder().decode(Computer.self, from: dictionary)
I am force-trying here to make the example shorter. In production code you should handle the errors appropriately.
I'm not sure if it's the best way but you definitely can do something like:
struct Foo: Codable {
var a: Int
var b: Int
init(a: Int, b: Int) {
self.a = a
self.b = b
}
}
let foo = Foo(a: 1, b: 2)
let dict = try JSONDecoder().decode([String: Int].self, from: JSONEncoder().encode(foo))
print(dict)
let dict = try JSONSerialization.jsonObject(with: try JSONEncoder().encode(struct), options: []) as? [String: Any]
I have modified the PropertyListEncoder from the Swift project into a DictionaryEncoder, simply by removing the final serialisation from dictionary into binary format. You can do the same yourself, or you can take my code from here
It can be used like this:
do {
let employeeDictionary: [String: Any] = try DictionaryEncoder().encode(employee)
} catch let error {
// handle error
}
In some project, i'm used the swift reflection. But be careful, nested codable objects, are not mapped also there.
let dict = Dictionary(uniqueKeysWithValues: Mirror(reflecting: foo).children.map{ ($0.label!, $0.value) })
I definitely think that there's some value in just being able to use Codable to encode to/from dictionaries, without the intention of ever hitting JSON/Plists/whatever. There are plenty of APIs which just give you back a dictionary, or expect a dictionary, and it's nice to be able to interchange them easily with Swift structs or objects, without having to write endless boilerplate code.
I've been playing round with some code based on the Foundation JSONEncoder.swift source (which actually does implement dictionary encoding/decoding internally, but doesn't export it).
The code can be found here: https://github.com/elegantchaos/DictionaryCoding
It's still quite rough, but I've expanded it a bit so that, for example, it can fill in missing values with defaults when decoding.
Here is a protocol based solution:
protocol DictionaryEncodable {
func encode() throws -> Any
}
extension DictionaryEncodable where Self: Encodable {
func encode() throws -> Any {
let jsonData = try JSONEncoder().encode(self)
return try JSONSerialization.jsonObject(with: jsonData, options: .allowFragments)
}
}
protocol DictionaryDecodable {
static func decode(_ dictionary: Any) throws -> Self
}
extension DictionaryDecodable where Self: Decodable {
static func decode(_ dictionary: Any) throws -> Self {
let jsonData = try JSONSerialization.data(withJSONObject: dictionary, options: [])
return try JSONDecoder().decode(Self.self, from: jsonData)
}
}
typealias DictionaryCodable = DictionaryEncodable & DictionaryDecodable
And here is how to use it:
class AClass: Codable, DictionaryCodable {
var name: String
var age: Int
init(name: String, age: Int) {
self.name = name
self.age = age
}
}
struct AStruct: Codable, DictionaryEncodable, DictionaryDecodable {
var name: String
var age: Int
}
let aClass = AClass(name: "Max", age: 24)
if let dict = try? aClass.encode(), let theClass = try? AClass.decode(dict) {
print("Encoded dictionary: \n\(dict)\n\ndata from decoded dictionary: \"name: \(theClass.name), age: \(theClass.age)\"")
}
let aStruct = AStruct(name: "George", age: 30)
if let dict = try? aStruct.encode(), let theStruct = try? AStruct.decode(dict) {
print("Encoded dictionary: \n\(dict)\n\ndata from decoded dictionary: \"name: \(theStruct.name), age: \(theStruct.age)\"")
}
I wrote a quick gist to handle this (not using the Codable protocol). Be careful, it doesn't type-check any values and doesn't work recursively on values that are encodable.
class DictionaryEncoder {
var result: [String: Any]
init() {
result = [:]
}
func encode(_ encodable: DictionaryEncodable) -> [String: Any] {
encodable.encode(self)
return result
}
func encode<T, K>(_ value: T, key: K) where K: RawRepresentable, K.RawValue == String {
result[key.rawValue] = value
}
}
protocol DictionaryEncodable {
func encode(_ encoder: DictionaryEncoder)
}
There no straight forward way of doing this in Codable. You need to implement Encodable/Decodable protocol for your struct. For your example, you might need to write as below
typealias EventDict = [String:Int]
struct Favorite {
var all:EventDict
init(all: EventDict = [:]) {
self.all = all
}
}
extension Favorite: Encodable {
struct FavoriteKey: CodingKey {
var stringValue: String
init?(stringValue: String) {
self.stringValue = stringValue
}
var intValue: Int? { return nil }
init?(intValue: Int) { return nil }
}
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: FavoriteKey.self)
for eventId in all {
let nameKey = FavoriteKey(stringValue: eventId.key)!
try container.encode(eventId.value, forKey: nameKey)
}
}
}
extension Favorite: Decodable {
public init(from decoder: Decoder) throws {
var events = EventDict()
let container = try decoder.container(keyedBy: FavoriteKey.self)
for key in container.allKeys {
let fav = try container.decode(Int.self, forKey: key)
events[key.stringValue] = fav
}
self.init(all: events)
}
}
I have made a pod here https://github.com/levantAJ/AnyCodable to facilitate decode and encode [String: Any] and [Any]
pod 'DynamicCodable', '1.0'
And you are able to decode & encode [String: Any] and [Any]
import DynamicCodable
struct YourObject: Codable {
var dict: [String: Any]
var array: [Any]
var optionalDict: [String: Any]?
var optionalArray: [Any]?
enum CodingKeys: String, CodingKey {
case dict
case array
case optionalDict
case optionalArray
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
dict = try values.decode([String: Any].self, forKey: .dict)
array = try values.decode([Any].self, forKey: .array)
optionalDict = try values.decodeIfPresent([String: Any].self, forKey: .optionalDict)
optionalArray = try values.decodeIfPresent([Any].self, forKey: .optionalArray)
}
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(dict, forKey: .dict)
try container.encode(array, forKey: .array)
try container.encodeIfPresent(optionalDict, forKey: .optionalDict)
try container.encodeIfPresent(optionalArray, forKey: .optionalArray)
}
}
After research, we find that if we use the keyword Any in the class which is inherited from the Codable & Decodable it will give the error. So if you want to use a dictionary user with the types of data coming from the server.
For example, the server is sending the dictionary of type [String : Int] then use [String : Int] if you will try [String : Any] it will not work.
Here is dictionary -> object. Swift 5.
extension Dictionary where Key == String, Value: Any {
func object<T: Decodable>() -> T? {
if let data = try? JSONSerialization.data(withJSONObject: self, options: []) {
return try? JSONDecoder().decode(T.self, from: data)
} else {
return nil
}
}
}
Come to think of it, the question does not have an answer in the general case, since the Encodable instance may be something not serializable into a dictionary, such as an array:
let payload = [1, 2, 3]
let encoded = try JSONEncoder().encode(payload) // "[1,2,3]"
Other than that, I have written something similar as a framework.
I am trying to create a dictionary extension where Dictionary is of the type <String, AnyObject>.
Was looking in many places and trying different approaches, but none of them seemed to work. This was one of them:
extension Dictionary where <String, AnyObject>{
var jsonString:String {
return ""
}
}
Another method that didn't actually work for some reason:
extension Dictionary where Key:Hashable, Value:AnyObject {
var jsonString:String {
do {
let stringData = try NSJSONSerialization.dataWithJSONObject(self, options: NSJSONWritingOptions.PrettyPrinted)
if let string = String(data: stringData, encoding: NSUTF8StringEncoding){
return string
}
}catch _ {
}
return ""
}
}
Got: Argument type 'Dictionary' does not conform to expected type of 'AnyObject'
>=3.1
From 3.1, we can do concrete extensions, ie:
extension Dictionary where Key == String {}
<3.1
We can not conform concrete types w/ concrete generics, ie:
extension Dictionary where Key == String
However, because Dictionary conforms to sequence and we can conform protocol types w/ concrete generics, we could do:
extension Sequence where Iterator.Element == (key: String, value: AnyObject) {
func doStuff() {...
Otherwise, we can constrain our key to a protocol that string conforms to like this:
extension Dictionary where Key: StringLiteralConvertible, Value: AnyObject {
var jsonString: String {
return ""
}
}
As per your updated answer. Json serialization needs an object, Swift Dictionaries are structs. You need to convert to an NSDictionary You must specify Key to conform to NSObject to properly convert to an NSDictionary.
Small note: Dictionaries already type constrain Key to be Hashable, so your original constraint wasn't adding anything.
extension Dictionary where Key: NSObject, Value:AnyObject {
var jsonString:String {
do {
let stringData = try NSJSONSerialization.dataWithJSONObject(self as NSDictionary, options: NSJSONWritingOptions.PrettyPrinted)
if let string = String(data: stringData, encoding: NSUTF8StringEncoding){
return string
}
}catch _ {
}
return ""
}
}
Note, that the dictionaries must conform to this type to access the extension.
let dict = ["k" : "v"]
Will become type [String : String], so you must be explicit in declaring:
let dict: [NSObject : AnyObject] = ["k" : "v"]
Swift 3 Approach
extension Dictionary where Key: ExpressibleByStringLiteral, Value: AnyObject
As StringLiteralConvertible is now deprecated and replaced by ExpressibleByStringLiteral
Update for Swift 3
Here is my example using ExpressibleByStringLiteral for Key and Any for Value.
extension Dictionary where Key: StringLiteralConvertible, Value: Any {
var jsonString: String? {
if let dict = (self as AnyObject) as? Dictionary<String, AnyObject> {
do {
let data = try JSONSerialization.data(withJSONObject: dict, options: JSONSerialization.WritingOptions(rawValue: UInt.allZeros))
if let string = String(data: data, encoding: String.Encoding.utf8) {
return string
}
} catch {
print(error)
}
}
return nil
}
}
and then I use it like this:
let dict: Dictionary<String, AnyObject> = [...]
let jsonString = dict.jsonString
You can convert self to AnyObject or NSObject, both works, then you do unwrap as Dictionary or any other specific type.
Adding to the answer provided by #Logan, for those looking to add custom properties to the string-subscripted Dictionary, that is possible as well (was looking to do this when I came across this SO question):
extension Dictionary where Key: StringLiteralConvertible {
var somePropertyThatIsAColor:UIColor? {
get {
return self["someKey"] as? UIColor
}
set {
// Have to cast as optional Value
self["someKey"] = (newValue as? Value)
}
}
Anyone using [String:Any] instead of Dictionary can use below extension
extension Dictionary where Key == String, Value == Any {
mutating func append(anotherDict:[String:Any]) {
for (key, value) in anotherDict {
self.updateValue(value, forKey: key)
}
}
}
So, Dictionary is:
public struct Dictionary<Key : Hashable, Value> : CollectionType, DictionaryLiteralConvertible {..}
How about a protocol extension? :D
extension CollectionType where Self: DictionaryLiteralConvertible, Self.Key == String, Self.Value == AnyObject, Generator.Element == (Self.Key, Self.Value) {
...
}
I was not able to make any of the offered solutions work in Swift 3, but by taking advantage of bridging between Dictionary and NSDictionary I could make this work:
extension NSDictionary {
var jsonString:String {
do {
let stringData = try JSONSerialization.data(withJSONObject: self, options: .prettyPrinted)
if let string = String(data: stringData, encoding: .utf8) {
return string
}
}catch _ {
}
return ""
}
}
I am trying to create a dictionary extension where Dictionary is of the type <String, AnyObject>.
Was looking in many places and trying different approaches, but none of them seemed to work. This was one of them:
extension Dictionary where <String, AnyObject>{
var jsonString:String {
return ""
}
}
Another method that didn't actually work for some reason:
extension Dictionary where Key:Hashable, Value:AnyObject {
var jsonString:String {
do {
let stringData = try NSJSONSerialization.dataWithJSONObject(self, options: NSJSONWritingOptions.PrettyPrinted)
if let string = String(data: stringData, encoding: NSUTF8StringEncoding){
return string
}
}catch _ {
}
return ""
}
}
Got: Argument type 'Dictionary' does not conform to expected type of 'AnyObject'
>=3.1
From 3.1, we can do concrete extensions, ie:
extension Dictionary where Key == String {}
<3.1
We can not conform concrete types w/ concrete generics, ie:
extension Dictionary where Key == String
However, because Dictionary conforms to sequence and we can conform protocol types w/ concrete generics, we could do:
extension Sequence where Iterator.Element == (key: String, value: AnyObject) {
func doStuff() {...
Otherwise, we can constrain our key to a protocol that string conforms to like this:
extension Dictionary where Key: StringLiteralConvertible, Value: AnyObject {
var jsonString: String {
return ""
}
}
As per your updated answer. Json serialization needs an object, Swift Dictionaries are structs. You need to convert to an NSDictionary You must specify Key to conform to NSObject to properly convert to an NSDictionary.
Small note: Dictionaries already type constrain Key to be Hashable, so your original constraint wasn't adding anything.
extension Dictionary where Key: NSObject, Value:AnyObject {
var jsonString:String {
do {
let stringData = try NSJSONSerialization.dataWithJSONObject(self as NSDictionary, options: NSJSONWritingOptions.PrettyPrinted)
if let string = String(data: stringData, encoding: NSUTF8StringEncoding){
return string
}
}catch _ {
}
return ""
}
}
Note, that the dictionaries must conform to this type to access the extension.
let dict = ["k" : "v"]
Will become type [String : String], so you must be explicit in declaring:
let dict: [NSObject : AnyObject] = ["k" : "v"]
Swift 3 Approach
extension Dictionary where Key: ExpressibleByStringLiteral, Value: AnyObject
As StringLiteralConvertible is now deprecated and replaced by ExpressibleByStringLiteral
Update for Swift 3
Here is my example using ExpressibleByStringLiteral for Key and Any for Value.
extension Dictionary where Key: StringLiteralConvertible, Value: Any {
var jsonString: String? {
if let dict = (self as AnyObject) as? Dictionary<String, AnyObject> {
do {
let data = try JSONSerialization.data(withJSONObject: dict, options: JSONSerialization.WritingOptions(rawValue: UInt.allZeros))
if let string = String(data: data, encoding: String.Encoding.utf8) {
return string
}
} catch {
print(error)
}
}
return nil
}
}
and then I use it like this:
let dict: Dictionary<String, AnyObject> = [...]
let jsonString = dict.jsonString
You can convert self to AnyObject or NSObject, both works, then you do unwrap as Dictionary or any other specific type.
Adding to the answer provided by #Logan, for those looking to add custom properties to the string-subscripted Dictionary, that is possible as well (was looking to do this when I came across this SO question):
extension Dictionary where Key: StringLiteralConvertible {
var somePropertyThatIsAColor:UIColor? {
get {
return self["someKey"] as? UIColor
}
set {
// Have to cast as optional Value
self["someKey"] = (newValue as? Value)
}
}
Anyone using [String:Any] instead of Dictionary can use below extension
extension Dictionary where Key == String, Value == Any {
mutating func append(anotherDict:[String:Any]) {
for (key, value) in anotherDict {
self.updateValue(value, forKey: key)
}
}
}
So, Dictionary is:
public struct Dictionary<Key : Hashable, Value> : CollectionType, DictionaryLiteralConvertible {..}
How about a protocol extension? :D
extension CollectionType where Self: DictionaryLiteralConvertible, Self.Key == String, Self.Value == AnyObject, Generator.Element == (Self.Key, Self.Value) {
...
}
I was not able to make any of the offered solutions work in Swift 3, but by taking advantage of bridging between Dictionary and NSDictionary I could make this work:
extension NSDictionary {
var jsonString:String {
do {
let stringData = try JSONSerialization.data(withJSONObject: self, options: .prettyPrinted)
if let string = String(data: stringData, encoding: .utf8) {
return string
}
}catch _ {
}
return ""
}
}