Currently I've got this chunky reduce function...
blah: [String: Any] = queryItems.reduce([String: Any]()) {
(params: [String: Any], queryItem: URLQueryItem) in
var output = params
output[queryItem.name] = queryItem.value
return output
}
I'm sure there is a much simpler way of doing this but I can't get my head around how that would work.
Is there a "better" way to do this?
By "better" I mean cleaner, shorter, more elegant, etc...
It's possible to use reduce(into:_:) instead of reduce(_:_). This both save you the lines and the overhead of copying params for each iteration:
let blah: [String: Any] = (urlComponents.queryItems ?? []).reduce(into: [:]) {
params, queryItem in
params[queryItem.name] = queryItem.value
}
This method is preferred over reduce(_:_:) for efficiency when the result is a copy-on-write type, for example an Array or a Dictionary.
You can create a dictionary from the name and value of each query item with
let items = urlComponents.queryItems ?? []
let dict = Dictionary(items.lazy.map { ($0.name, $0.value as Any) },
uniquingKeysWith: { $1 })
In the case of a duplicate name, the later value wins (this can be controlled with the uniquingKeysWith: parameters).
Or remove the as Any cast to get a dictionary of type [String: String?]:
let items = urlComponents.queryItems ?? []
let dict = Dictionary(items.lazy.map { ($0.name, $0.value ) },
uniquingKeysWith: { $1 })
Alternatively
let items = urlComponents.queryItems ?? []
let dict = Dictionary(items.lazy.map { ($0.name, [$0.value] ) },
uniquingKeysWith: +)
to build a dictionary of type [String : [String?]], holding all values for each name.
Related
My problem is that this code is case-sensitive. If I have "Sam" and "sam", they will be sorted into different keys. Any way that I can think of doing this is by converting the string into all lowercase, but I want it to stay as normal while being sorted without case-sensitivity:
var dict: [String: [String]] = [:]
for string in array {
if (dict[string] != nil) {
dict[string]?.append(string)
}
else {
dict[string] = [string]
}
}
As it is right now my code would result in:
["Sam": ["Sam"], "sam", ["sam"]]
Instead of what I want:
["Sam": ["Sam", "sam"]]
How can I accomplish this?
You can use reduce(into:) method and assign each element capitalized to the result:
let array = ["Sam", "sam", "SAM"]
let dict: [String: [String]] = array.reduce(into: [:]) {
$0[$1.capitalized, default: []].append($1)
}
print(dict) // ["Sam": ["Sam", "sam", "SAM"]]
If you just want to have case insensitive keys and case sensitive values, from given array, the shortest solution could be something like this:
var dict: [String: [String]] = [:]
array.forEach { dict[$0.lowercased(), default: []] += [$0] }
Here is my Array of Dictionary,
var myArrayOfDict = [["vegetables": ["CARROT","BEANS"], "fruits": ["APPLE","MANGO","BANANA"], "letters":["A","B","C","D"],"numbers":["ONE","TWO","THREE"],"shapes":["SQUARE","RECTANGLE","CIRCLE"]]]
How do i get the desired output, actually i need to get random selected elements of the specified range ...(i.e) when i need 3 elements randomnly from dictionary as like,
[["fruits": ["APPLE","MANGO","BANANA"],"shapes":["SQUARE","RECTANGLE","CIRCLE"],"numbers":["ONE","TWO","THREE"]]]
When i need just 2 elements randomnly like,
[["shapes":["SQUARE","RECTANGLE","CIRCLE"],"fruits": ["APPLE","MANGO","BANANA"]]]
Thanks in Advance,
Here is one solution using randomElement().
func randomSelection(from dict: [String: [String]], count: Int) -> [String: [String]] {
guard !dict.isEmpty else { return [:] }
var result = [String: [String]]()
for i in 0..<count {
let element = dict.randomElement()! //We know dictionary is not empty
result[element.key] = element.value
}
return result
}
The above solution might return less elements in a dictionary than expected if the same element is returned more than once from randomElemnt(). If this should be voided the below solution should work
func randomSelection(from dict: [String: [String]], count: Int) -> [String: [String]] {
guard !dict.isEmpty else { return [:] }
guard dict.count > count else { return dict }
var result = [String: [String]]()
while result.count < count {
let element = dict.randomElement()!
if result[element.key] == nil {
result[element.key] = element.value
}
}
return result
}
Since the function takes a dictionary as the first argument the array needs to be looped over
for d in myArrayOfDict {
print(randomSelection(from: d, count: 2))
}
Array myArrayOfDict contains a single Dictionary. So, it doesn't make sense getting a random element from it.
As your example explains, you need to get random elements from the Dictionary itself.
So, you can use randomElement to get that working.
let myArrayOfDict = ["vegetables": ["CARROT","BEANS"], "fruits": ["APPLE","MANGO","BANANA"], "letters":["A","B","C","D"],"numbers":["ONE","TWO","THREE"],"shapes":["SQUARE","RECTANGLE","CIRCLE"]]
var elements = [String : [String]]()
let count = 2
for _ in 0..<count {
if let element = myArrayOfDict.randomElement() {
elements[element.key] = element.value
}
}
print(elements)
I have swift dictionary [String: Any] which I store in UserDefauls as an array [[String: Any]]
what I want to do is replace key: value with another one, e.g. "id": "x:coredataid"with"id": "server id"
I need to loop through array first and then through all key values. Is there any elegant solution for this purposes?
If not how then simple iterate through all key values and all nested levels in dictionary?
I have this code: for (key, value) in params
but it's only for top level keys.
Let me explain more in details. As you see I have phases key which an array. Also each phase contains day key which also an array.
So I don't care actually about key naming, phases it or days whether, what I want is to iterate all of key, values from provided [String: Any] dictionary and check if key contains a value which equal provided string.
As you see currently workoutId equals: <x-coredata://C3C82F5A-8709-4EDC-8AE5-C23C65F220D5/WorkoutEntity/t072831FB-8F5C-4589-85CB-6D084671C097815> I underscore it with red line.
So I want to loop a dictionary to catch this key workoutId and check if this equal <x-coredata://C3C82F5A-8709-4EDC-8AE5-C23C65F220D5/WorkoutEntity/t072831FB-8F5C-4589-85CB-6D084671C097815>
One more time I don't care about workoutId name, key can be actually named as exerciseId or id never mind. I just want to find a value <x-coredata://C3C82F5A-8709-4EDC-8AE5-C23C65F220D5/WorkoutEntity/t072831FB-8F5C-4589-85CB-6D084671C097815> in my entire dictionary and if there are lot of them replace all of them.
The reason why I need it is connected to identifier I store localy which are equals to CoreData identifiers as you my noticed. But when I modified my CoreData records with new identifiers returned from server I want to replace my UserDefaults off-line requests store with new ids.
I've added also modification to this code:
func update(_ dict: [String: Any], set serverId: Any, for localId: String) -> [String: Any] {
var newDict = dict
for (k, v) in newDict {
if let mobileLocalId = v as? String {
if mobileLocalId == localId {
newDict[k] = serverId
} else { newDict[k] = v }
} else if let subDict = v as? [String: Any] {
newDict[k] = update(subDict, set: serverId, for: localId)
} else if let dictionaries = v as? [[String: Any]] {
for dictionary in dictionaries {
newDict[k] = update(dictionary, set: serverId, for: localId)
}
}
}
return newDict
}
but it somehow drop days for me and newDict now looks like this:
(lldb) po newDict
▿ 2 elements
▿ 0 : 2 elements
- key : "position"
- value : 0
▿ 1 : 2 elements
- key : "workoutId"
- value : "5d51723b3faceb53f9d2d5ed"
where actully I susscefully changed identifiers, but now all other key pairs from above example are missed.
Here is a solution with a recursive function that replaces all values for a given key.
func update(_ dict: [String: Any], set value: Any, for key: String) -> [String: Any] {
var newDict = dict
for (k, v) in newDict {
if k == key {
newDict[k] = value
} else if let subDict = v as? [String: Any] {
newDict[k] = update(subDict, set: value, for: key)
} else if let subArray = v as? [[String: Any]] {
var newArray = [[String: Any]]()
for item in subArray {
newArray.append(update(item, set: value, for: key))
}
newDict[k] = newArray
}
}
return newDict
}
Note that it doesn't check what type the existing value is but directly replaces it with the new value. Also the code assumes the only types of nested arrays are arrays of dictionaries.
For the array this function can be used with map
let out = data.map { update($0, set: "newValue", for: "id")}
This recursive function will iterate through all key values:
func iterateThroughAllKeyValues<Key: Hashable, Value>(of dictionary: Dictionary<Key, Value>, execute execution: ((Key, Value))->()) {
for element in dictionary {
if let dictionary = element.value as? [Key: Value] {
iterateThroughAllKeyValues(of: dictionary, execute: execution)
} else {
execution(element)
}
}
}
Also you can achieve calling execution on the main node of any nested dictionary with a little bit of change.
And this is the extension mode:
extension Dictionary {
func iterateThroughAllKeyValues(execute execution: ((Key, Value))->()) {
for element in self {
if let dictionary = element.value as? [Key: Value] {
dictionary.iterateThroughAllKeyValues(execute: execution)
} else {
execution(element)
}
}
}
}
Note: Careful about the order
Usage Example:
let dictionary: [String: Any] = [
"id0": "value0",
"nested": ["id1": "value1"],
"nestedNested": ["id2": "value2",
"nested": ["id3": "value3"]]
]
dictionary.iterateThroughAllKeyValues { (key, value) in
print("key:", key, "Value:", value)
}
Output:
key: id0 Value: value0
key: id1 Value: value1
key: id3 Value: value3
key: id2 Value: value2
I can print this in the debugger:
(lldb) print params["message"]!
([String : String]) $R5 = 2 key/value pairs {
[0] = (key = "body", value = "iPadUser has started a new stream")
[1] = (key = "title", value = "Stream started")
}
But I am trying to figure out how to access the body and title separately.
I construct params in this way:
let recipients = ["custom_ids":[recips]]
let notificationDetails = "hello there"
let content = [
"title":title,
"body":details
]
let params: [String:Any] = [
"group_id":"stream_requested",
"recipients": recipients,
"message": content
]
print((params["message"] as! [String: Any])["title"] as! String)
You need to cast the Dictionary value as specific type, since the compiler doesn't know what to expect. (Please mind that you mustn't use force unwrap in other way than example code.)
Considering you need to fetch array values when recipients dictionary looks like this:
let recipients = ["custom_ids":["recipe1", "recipe2", "etc"]]
get to the ids like this:
guard let recipients = params["recipients"] as? [String: Any],
let customIDs = recipients["custom_ids"] as? [String]
else { return }
for id in customIDs {
print(id) // Gets your String value
}
I have a class in my app, where the user inputs values and i set them to an instance of the class, then i upload this data to Database, but i have to convert the class to something the database accepts and i'm converting to dictionary using Mirror Reflection. Some properties in my class can be nil, because by design not all properties are required. But i can't pass nil values to the database.
I have recreated my example is very simplified playground. i didn't set a value for the name property of the class
I tried to check for nil before adding the key, value pair to the dictionary
Below is my code
import UIKit
class Color: NSObject {
var name: String?
var code: Int?
var shade: String?
}
let cl = Color()
cl.code = 3456
cl.shade = "DARK"
var colorDict = [String: Any]()
for x in Mirror(reflecting: cl).children.makeIterator() {
if let val = x.value as Any? {
print(type(of: val))
colorDict[x.label!] = val
}
}
print (colorDict)
the output in console is as below
Optional<String>
Optional<Int>
Optional<String>
["name": nil, "code": Optional(3456), "shade": Optional("DARK")]
how can i check for nil values and skip adding that property to the Dictionary
i have tried to loop through the dictionary after i add all values including nils and check for values too but i get the below warning
Comparing non-optional value of type 'Any' to nil always returns false
declaring the dictionary as below
var colorDict = [String: Any?]()
for x in colorDict {
if x.value == nil {
colorDict.removeValue(forKey: x.key)
}
}
removes the warning but it doesn't remove anything.
I would really appreciate your help.
The way of unwrapping objects of type Any that contain optionals is kind of weird but you can check that the values aren't nil in your mirror like this:
for x in Mirror(reflecting: cl).children {
if case Optional<Any>.some(let val) = x.value {
print(type(of: val))
colorDict[x.label!] = val
}
}
You can do this really easily in a one-liner, using filter:
let dict: [String : Any?] = ["Foo" : 3, "Bar" : nil, "Baz" : "Qux"]
let noNils = dict.filter { $0.value != nil }
print(noNils) // prints ["Foo": Optional(3), "Baz": Optional("Qux")]
As i have suggested, initialise all values.
If you decide not to store the nil values you will end up with children that some of them will have 1, some 2 and some 3 nodes, nothing wrong with that, BUT what happens when you go to read them?
You havent shared any info as to how these values will be used by the app, but assuming you have one function to read the properties/nodes of stored colors, it will go to read all 3 :
ref.child("colors").child("someSpecificColor").observeSingleEvent(of: .value, with: { (snapshot) in
// Get color values
let value = snapshot.value as? NSDictionary
let name = value?["name"] as? String ?? ""
let code = value?["code"] as? String ?? ""
let shade = value?["shade"] as? String ?? ""
// ...
}) { (error) in
print(error.localizedDescription)
}
See the issue?
Here is a simple solution :
var colorDict = [String: Any?]()
for x in Mirror(reflecting: cl).children.makeIterator() {
if let val = x.value, val != nil {
print(type(of: val))
colorDict[x.label!] = val
}
}
Here before to print and add you val, you check if the val is different than nil. As your output suggests in your console log you print :
Optional<String>
Optional<Int>
Optional<String>
val is an optional. So, if it's nil it won't be added. If not, you enter into the if statement and that's it.