I'm trying to deal with an app in Swift and I'm facing the following error using arrays:
fatal error: Array index out of range
This appears when apps assign a value to the array at index 0:
class DrawScene: SKScene {
init(size: CGSize) {
super.init(size: size)
}
var line = SKShapeNode()
var path = CGPathCreateMutable()
var touch: UITouch!
var pts = [CGPoint]()
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
touch = touches.anyObject() as UITouch!
self.pts[0] = touch.locationInNode(self) <-- Error appears here
drawLine()
}
Some ideas? (I'm using xcode 6 Beta 4)
Your array is empty at first.
if self.pts.isEmpty {
self.pts.append(touch.locationInNode(self))
}
else {
self.pts[0] = touch.locationInNode(self)
}
As it says in the docs:
“You can’t use subscript syntax to append a new item to the end of an array. If you try to use subscript syntax to retrieve or set a value for an index that is outside of an array’s existing bounds, you will trigger a runtime error.”
You'll have to use append or += to add to an empty array. If you always want to set this point to the first object in the array, replacing anything already there, you'll have to check the count of the array first.
I don't recommend this to anyone, but you could implement your own subscript that allows you to do this:
extension Array {
subscript(safe index: Int) -> Element? {
get {
return self.indices.contains(index) ? self[index] : nil
}
set(newValue) {
guard let newValue = newValue { return }
if self.count == index {
self.append(newValue)
} else {
self[index] = newValue
}
}
}
}
And you can use this as expected:
var arr = [String]()
arr[safe: 0] = "Test"
arr[safe: 1] = "Test2"
print(arr) // ["Test", "Test2"]
arr[safe: 0] = "Test0"
print(arr) // ["Test0", "Test2"]
arr[safe: 3] = "Test2" // fatal error: Index out of range
Related
Related to this question, but a different error: Other Question
I have tried both the Swift 3 as well as the Swift 4 code from this question:
Shuffle Link
I am using Swift 3.2, and when using the Swift 3 code it yelled at me for not using SwapAt, so I've included the Swift 4 code, but I tried both, with the same result.
When using the shuffle() method, I get the error Variable 'offerCardsShuffled' inferred to have type '()', which may be unexpected, and the obvious error afterwards, Value of tuple type '()' has no member 'enumerated'
I'm not sure what would be causing this, as other people using this code don't seem to be having that problem. Why are my shuffled arrays coming up as empty tuples?
Note I am fairly new to Swift development so a thorough explanation is definitely helpful.
func displayOfferCards() -> Void {
//let offerCardsr = allOfferCards().reversed()
var offerCards = allOfferCards()
var offerCardsShuffled = offerCards.shuffle()
for (index, offerCard) in offerCardsShuffled.enumerated() {
let delay = Double(index) * 0.2
offerCard.display(delay: delay)
}
}
}
func allOfferCards() -> [OfferCard]{
guard dataSource != nil else {
return []
}
let numberOfCards = self.dataSource!.kolodaNumberOfCards(self)
var offerCards = [OfferCard]()
for i in 0..<numberOfCards {
let offerCard = viewForCard(at: i)
if let offerCard = offerCard {
offerCards.append(offerCard as! OfferCard)
}
}
return offerCards
}
extension MutableCollection {
/// Shuffles the contents of this collection.
mutating func shuffle() {
let c = count
guard c > 1 else { return }
for (firstUnshuffled, unshuffledCount) in zip(indices, stride(from: c, to: 1, by: -1)) {
let d: IndexDistance = numericCast(arc4random_uniform(numericCast(unshuffledCount)))
let i = index(firstUnshuffled, offsetBy: d)
swapAt(firstUnshuffled, i)
}
}
}
extension Sequence {
/// Returns an array with the contents of this sequence, shuffled.
func shuffled() -> [Element] {
var result = Array(self)
result.shuffle()
return result
}
}
Your shuffle method modifies the original collection, it does not return a new collection.
Change:
var offerCardsShuffled = offerCards.shuffle()
to:
offerCards.shuffle()
and replace the use of offerCardsShuffled with offerCards in the remaining code.
I want to return the first item in a given array of custom objects and return an array of indices and the first custom object element so I can wrap a guard statement around it.
ie:
let firstOrder = existingOrders.enumerated().flatMap{$0,$1}.first
or attempt #1
let array = existingOrders.enumerated().map { (a, b) in return [$0.index : $1.element] }.first
or attempt #2
let array = existingOrders.enumerated().map { ($0.offset, $0.element) }.first
print (array)
This isn't returning the actual object; and it seems to return a tuple.
where
existingOrders = [ExistingOrder, EngineYard.ExistingOrder, EngineYard.ExistingOrder]
it returns the following;
[(0, EngineYard.ExistingOrder), (1, EngineYard.ExistingOrder), (2, EngineYard.ExistingOrder)]
attempt #3;
let array = existingOrders.enumerated().map { ($0.offset, $0.element) }
print (array)
guard let firstOrder = array.first else {
break
}
print (firstOrder) // should be a tuple of index and custom object
How do I grab the optional first item in an array and return index and element?
Many thanks
Edit. the reason I'm doing this is so that I can transfer the correct object to another class.
// transfer all
while (factory.existingOrders.count > 0) {
let array = myOrderBook.existingOrders.enumerated().map { ($0.offset, $0.element) }
guard let firstOrder = array.first else {
break
}
let index = (firstOrder.0)
factory.orderBook.transfer(index: index, destination: .completedOrder)
}
Where the Orderbook is a class;
Factory {
var orderBook:OrderBook = OrderBook()
}
OrderBook {
var existingOrders: [ExistingOrder] = [ExistingOrder]()
var completedOrders: [CompletedOrder] = [CompletedOrder]()
}
And the idea is that I want to transfer an object from existing orders to completed orders and vice versa
The function requires an index, but I guess I could refactor it so I can transfer an object instead.
The answer I was looking for was;
let array = myOrderBook.existingOrders.enumerated().map { ($0.offset, $0.element) }
However, I found that my code needed to be refactored.
Thanks.
Issue closed.
What woudl be a simple way to reduce a string like AAA:111;BBB:222;333;444;CCC:555 to a dictionary in Swift. I have the following code:
var str = "AAA:111;BBB:222;333;444;CCC:555"
var astr = str.componentsSeparatedByString(";").map { (element) -> [String:String] in
var elements = element.componentsSeparatedByString(":")
if elements.count < 2 {
elements.insert("N/A", atIndex: 0)
}
return [elements[0]:elements[1]]
}
The code above produces an Array of Dictionaries:
[["A": "111"], ["BBB": "222"], ["UKW": "333"], ["UKW": "444"], ["CCC": "555"]]
I want it to produce
["A": "111", "BBB": "222", "UKW": "333", "UKW": "444", "CCC": "555"]
but no mater what I try, since i call the map function on an Array it seems impossible to convert the nature of the map function's result.
NOTE: The dictionary in string format is described as either having KEY:VALUE; format or VALUE; format, in which case the mapping function will add the "N/A" as being the key of the unnamed value.
Any help on this matter is greatly appreciated.
Your map produces an array of dictionaries. When you want to combine them into 1, that's a perfect job for reduce:
func + <K,V>(lhs: Dictionary<K,V>, rhs: Dictionary<K,V>) -> Dictionary<K,V> {
var result = Dictionary<K,V>()
for (key, value) in lhs {
result[key] = value
}
for (key, value) in rhs {
result[key] = value
}
return result
}
var str = "AAA:111;BBB:222;333;444;CCC:555"
var astr = str
.componentsSeparatedByString(";")
.reduce([String: String]()) {
aggregate, element in
var elements = element.componentsSeparatedByString(":")
if elements.count < 2 {
elements.insert("N/A", atIndex: 0)
}
return aggregate + [elements[0]:elements[1]]
}
print(astr)
Swift has no default operator to "combine" two Dictionaries so you have to define one. Note that the + here is not commutative: dictA + dictB != dictB + dictA. If a key exist in both dictionaries, the value from the second dictionary will be used.
This is a work for reduce:
let str = "AAA:111;BBB:222;333;444;CCC:555"
let keyValueStrings = str.componentsSeparatedByString(";")
let dictionary = keyValueStrings.reduce([String: String]()) {
aggregate, element in
var newAggregate = aggregate
let elements = element.componentsSeparatedByString(":")
let key = elements[0]
// replace nil with the value you want to use if there is no value
let value = (elements.count > 1) ? elements[1] : nil
newAggregate[key] = value
return newAggregate
}
print(dictionary)
You can also make aggregate mutable directly:
let dictionary = keyValueStrings.reduce([String: String]()) {
(var aggregate: [String: String], element: String) -> [String: String] in
let elements = element.componentsSeparatedByString(":")
let key = elements[0]
// replace nil with the value you want to use if there is no value
let value = (elements.count > 1) ? elements[1] : nil
aggregate[key] = value
return aggregate
}
This is a functional approach, but you can achieve the same using a for iteration.
The reason this is happening is because map can only return arrays. If you are using this method to parse your string, then you need to convert it to a dictionary after.
var newDict = [String:String]()
for x in astr {
for (i, j) in x {
newDict[i] = j
}
}
The current issue with your code is that map function iterates over array containing [["key:value"],["key:value"]..] and you separate it again. But it returns ["key":"value"] which you then add to your array.
Instead you can add elements[0]:elements[1] directly to a locally kept variable which will fix your problem. Something like
finalVariable[elements[0]] = elements[1]
Suppose I have an array and I want to pick one element at random.
What would be the simplest way to do this?
The obvious way would be array[random index]. But perhaps there is something like ruby's array.sample? Or if not could such a method be created by using an extension?
Swift 4.2 and above
The new recommended approach is a built-in method on the Collection protocol: randomElement(). It returns an optional to avoid the empty case I assumed against previously.
let array = ["Frodo", "Samwise", "Merry", "Pippin"]
print(array.randomElement()!) // Using ! knowing I have array.count > 0
If you don't create the array and aren't guaranteed count > 0, you should do something like:
if let randomElement = array.randomElement() {
print(randomElement)
}
Swift 4.1 and below
Just to answer your question, you can do this to achieve random array selection:
let array = ["Frodo", "Samwise", "Merry", "Pippin"]
let randomIndex = Int(arc4random_uniform(UInt32(array.count)))
print(array[randomIndex])
The castings are ugly, but I believe they're required unless someone else has another way.
Riffing on what Lucas said, you could create an extension to the Array class like this:
extension Array {
func randomItem() -> Element? {
if isEmpty { return nil }
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
For example:
let myArray = [1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16]
let myItem = myArray.randomItem() // Note: myItem is an Optional<Int>
Swift 4 version:
extension Collection where Index == Int {
/**
Picks a random element of the collection.
- returns: A random element of the collection.
*/
func randomElement() -> Iterator.Element? {
return isEmpty ? nil : self[Int(arc4random_uniform(UInt32(endIndex)))]
}
}
In Swift 2.2 this can be generalised so that we have:
UInt.random
UInt8.random
UInt16.random
UInt32.random
UInt64.random
UIntMax.random
// closed intervals:
(-3...3).random
(Int.min...Int.max).random
// and collections, which return optionals since they can be empty:
(1..<4).sample
[1,2,3].sample
"abc".characters.sample
["a": 1, "b": 2, "c": 3].sample
First, implementing static random property for UnsignedIntegerTypes:
import Darwin
func sizeof <T> (_: () -> T) -> Int { // sizeof return type without calling
return sizeof(T.self)
}
let ARC4Foot: Int = sizeof(arc4random)
extension UnsignedIntegerType {
static var max: Self { // sadly `max` is not required by the protocol
return ~0
}
static var random: Self {
let foot = sizeof(Self)
guard foot > ARC4Foot else {
return numericCast(arc4random() & numericCast(max))
}
var r = UIntMax(arc4random())
for i in 1..<(foot / ARC4Foot) {
r |= UIntMax(arc4random()) << UIntMax(8 * ARC4Foot * i)
}
return numericCast(r)
}
}
Then, for ClosedIntervals with UnsignedIntegerType bounds:
extension ClosedInterval where Bound : UnsignedIntegerType {
var random: Bound {
guard start > 0 || end < Bound.max else { return Bound.random }
return start + (Bound.random % (end - start + 1))
}
}
Then (a little more involved), for ClosedIntervals with SignedIntegerType bounds (using helper methods described further below):
extension ClosedInterval where Bound : SignedIntegerType {
var random: Bound {
let foot = sizeof(Bound)
let distance = start.unsignedDistanceTo(end)
guard foot > 4 else { // optimisation: use UInt32.random if sufficient
let off: UInt32
if distance < numericCast(UInt32.max) {
off = UInt32.random % numericCast(distance + 1)
} else {
off = UInt32.random
}
return numericCast(start.toIntMax() + numericCast(off))
}
guard distance < UIntMax.max else {
return numericCast(IntMax(bitPattern: UIntMax.random))
}
let off = UIntMax.random % (distance + 1)
let x = (off + start.unsignedDistanceFromMin).plusMinIntMax
return numericCast(x)
}
}
... where unsignedDistanceTo, unsignedDistanceFromMin and plusMinIntMax helper methods can be implemented as follows:
extension SignedIntegerType {
func unsignedDistanceTo(other: Self) -> UIntMax {
let _self = self.toIntMax()
let other = other.toIntMax()
let (start, end) = _self < other ? (_self, other) : (other, _self)
if start == IntMax.min && end == IntMax.max {
return UIntMax.max
}
if start < 0 && end >= 0 {
let s = start == IntMax.min ? UIntMax(Int.max) + 1 : UIntMax(-start)
return s + UIntMax(end)
}
return UIntMax(end - start)
}
var unsignedDistanceFromMin: UIntMax {
return IntMax.min.unsignedDistanceTo(self.toIntMax())
}
}
extension UIntMax {
var plusMinIntMax: IntMax {
if self > UIntMax(IntMax.max) { return IntMax(self - UIntMax(IntMax.max) - 1) }
else { return IntMax.min + IntMax(self) }
}
}
Finally, for all collections where Index.Distance == Int:
extension CollectionType where Index.Distance == Int {
var sample: Generator.Element? {
if isEmpty { return nil }
let end = UInt(count) - 1
let add = (0...end).random
let idx = startIndex.advancedBy(Int(add))
return self[idx]
}
}
... which can be optimised a little for integer Ranges:
extension Range where Element : SignedIntegerType {
var sample: Element? {
guard startIndex < endIndex else { return nil }
let i: ClosedInterval = startIndex...endIndex.predecessor()
return i.random
}
}
extension Range where Element : UnsignedIntegerType {
var sample: Element? {
guard startIndex < endIndex else { return nil }
let i: ClosedInterval = startIndex...endIndex.predecessor()
return i.random
}
}
You can use Swift's built-in random() function as well for the extension:
extension Array {
func sample() -> Element {
let randomIndex = Int(rand()) % count
return self[randomIndex]
}
}
let array = [1, 2, 3, 4]
array.sample() // 2
array.sample() // 2
array.sample() // 3
array.sample() // 3
array.sample() // 1
array.sample() // 1
array.sample() // 3
array.sample() // 1
Another Swift 3 suggestion
private extension Array {
var randomElement: Element {
let index = Int(arc4random_uniform(UInt32(count)))
return self[index]
}
}
Following others answer but with Swift 2 support.
Swift 1.x
extension Array {
func sample() -> T {
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
Swift 2.x
extension Array {
func sample() -> Element {
let index = Int(arc4random_uniform(UInt32(self.count)))
return self[index]
}
}
E.g.:
let arr = [2, 3, 5, 7, 9, 11, 13, 17, 19, 23, 29, 31]
let randomSample = arr.sample()
An alternative functional implementation with check for empty array.
func randomArrayItem<T>(array: [T]) -> T? {
if array.isEmpty { return nil }
let randomIndex = Int(arc4random_uniform(UInt32(array.count)))
return array[randomIndex]
}
randomArrayItem([1,2,3])
Here's an extension on Arrays with an empty array check for more safety:
extension Array {
func sample() -> Element? {
if self.isEmpty { return nil }
let randomInt = Int(arc4random_uniform(UInt32(self.count)))
return self[randomInt]
}
}
You can use it as simple as this:
let digits = Array(0...9)
digits.sample() // => 6
If you prefer a Framework that also has some more handy features then checkout HandySwift. You can add it to your project via Carthage then use it exactly like in the example above:
import HandySwift
let digits = Array(0...9)
digits.sample() // => 8
Additionally it also includes an option to get multiple random elements at once:
digits.sample(size: 3) // => [8, 0, 7]
Swift 3
import GameKit
func getRandomMessage() -> String {
let messages = ["one", "two", "three"]
let randomNumber = GKRandomSource.sharedRandom().nextInt(upperBound: messages.count)
return messages[randomNumber].description
}
Swift 3 - simple easy to use.
Create Array
var arrayOfColors = [UIColor.red, UIColor.yellow, UIColor.orange, UIColor.green]
Create Random Color
let randomColor = arc4random() % UInt32(arrayOfColors.count)
Set that color to your object
your item = arrayOfColors[Int(randomColor)]
Here is an example from a SpriteKit project updating a SKLabelNode with a random String:
let array = ["one","two","three","four","five"]
let randomNumber = arc4random() % UInt32(array.count)
let labelNode = SKLabelNode(text: array[Int(randomNumber)])
If you want to be able to get more than one random element out of your array with no duplicates, GameplayKit has you covered:
import GameplayKit
let array = ["one", "two", "three", "four"]
let shuffled = GKMersenneTwisterRandomSource.sharedRandom().arrayByShufflingObjects(in: array)
let firstRandom = shuffled[0]
let secondRandom = shuffled[1]
You have a couple choices for randomness, see GKRandomSource:
The GKARC4RandomSource class uses an algorithm similar to that employed in arc4random family of C functions. (However, instances of this class are independent from calls to the arc4random functions.)
The GKLinearCongruentialRandomSource class uses an algorithm that is faster, but less random, than the GKARC4RandomSource class. (Specifically, the low bits of generated numbers repeat more often than the high bits.) Use this source when performance is more important than robust unpredictability.
The GKMersenneTwisterRandomSource class uses an algorithm that is slower, but more random, than the GKARC4RandomSource class. Use this source when it’s important that your use of random numbers not show repeating patterns and performance is of less concern.
I find using GameKit's GKRandomSource.sharedRandom() works best for me.
import GameKit
let array = ["random1", "random2", "random3"]
func getRandomIndex() -> Int {
let randomNumber = GKRandomSource.sharedRandom().nextIntWithUpperBound(array.count)
return randomNumber
or you could return the object at the random index selected. Make sure the function returns a String first, and then return the index of the array.
return array[randomNumber]
Short and to the point.
There is a built-in method on Collection now:
let foods = ["🍕", "🍔", "🍣", "🍝"]
let myDinner = foods.randomElement()
If you want to extract up to n random elements from a collection you can add an extension like this one:
extension Collection {
func randomElements(_ count: Int) -> [Element] {
var shuffledIterator = shuffled().makeIterator()
return (0..<count).compactMap { _ in shuffledIterator.next() }
}
}
And if you want them to be unique you can use a Set, but the elements of the collection must conform to the Hashable protocol:
extension Collection where Element: Hashable {
func randomUniqueElements(_ count: Int) -> [Element] {
var shuffledIterator = Set(shuffled()).makeIterator()
return (0..<count).compactMap { _ in shuffledIterator.next() }
}
}
Latest swift3 code try it its working fine
let imagesArray = ["image1.png","image2.png","image3.png","image4.png"]
var randomNum: UInt32 = 0
randomNum = arc4random_uniform(UInt32(imagesArray.count))
wheelBackgroundImageView.image = UIImage(named: imagesArray[Int(randomNum)])
I figured out a very different way to do so using the new features introduced in Swift 4.2.
// 👇🏼 - 1
public func shufflePrintArray(ArrayOfStrings: [String]) -> String {
// - 2
let strings = ArrayOfStrings
//- 3
var stringans = strings.shuffled()
// - 4
var countS = Int.random(in: 0..<strings.count)
// - 5
return stringans[countS]
}
we declared a function with parameters taking an array of Strings and returning a String.
Then we take the ArrayOfStrings in a variable.
Then we call the shuffled function and store that in a variable. (Only supported in 4.2)
Then we declare a variable which saves a shuffled value of total count of the String.
Lastly we return the shuffled string at the index value of countS.
It is basically shuffling the array of strings and then also have a random pick of number of the total number of count and then returning the random index of the shuffled array.
I want to store structs inside an array, access and change the values of the struct in a for loop.
struct testing {
var value:Int
}
var test1 = testing(value: 6 )
test1.value = 2
// this works with no issue
var test2 = testing(value: 12 )
var testings = [ test1, test2 ]
for test in testings{
test.value = 3
// here I get the error:"Can not assign to 'value' in 'test'"
}
If I change the struct to class it works. Can anyone tell me how I can change the value of the struct.
Besides what said by #MikeS, remember that structs are value types. So in the for loop:
for test in testings {
a copy of an array element is assigned to the test variable. Any change you make on it is restricted to the test variable, without doing any actual change to the array elements. It works for classes because they are reference types, hence the reference and not the value is copied to the test variable.
The proper way to do that is by using a for by index:
for index in 0..<testings.count {
testings[index].value = 15
}
in this case you are accessing (and modifying) the actual struct element and not a copy of it.
Well I am going to update my answer for swift 3 compatibility.
When you are programming many you need to change some values of objects that are inside a collection. In this example we have an array of struct and given a condition we need to change the value of a specific object. This is a very common thing in any development day.
Instead of using an index to determine which object has to be modified I prefer to use an if condition, which IMHO is more common.
import Foundation
struct MyStruct: CustomDebugStringConvertible {
var myValue:Int
var debugDescription: String {
return "struct is \(myValue)"
}
}
let struct1 = MyStruct(myValue: 1)
let struct2 = MyStruct(myValue: 2)
let structArray = [struct1, struct2]
let newStructArray = structArray.map({ (myStruct) -> MyStruct in
// You can check anything like:
if myStruct.myValue == 1 {
var modified = myStruct
modified.myValue = 400
return modified
} else {
return myStruct
}
})
debugPrint(newStructArray)
Notice all the lets, this way of development is safer.
The classes are reference types, it's not needed to make a copy in order to change a value, like it happens with structs. Using the same example with classes:
class MyClass: CustomDebugStringConvertible {
var myValue:Int
init(myValue: Int){
self.myValue = myValue
}
var debugDescription: String {
return "class is \(myValue)"
}
}
let class1 = MyClass(myValue: 1)
let class2 = MyClass(myValue: 2)
let classArray = [class1, class2]
let newClassArray = classArray.map({ (myClass) -> MyClass in
// You can check anything like:
if myClass.myValue == 1 {
myClass.myValue = 400
}
return myClass
})
debugPrint(newClassArray)
To simplify working with value types in arrays you could use following extension (Swift 3):
extension Array {
mutating func modifyForEach(_ body: (_ index: Index, _ element: inout Element) -> ()) {
for index in indices {
modifyElement(atIndex: index) { body(index, &$0) }
}
}
mutating func modifyElement(atIndex index: Index, _ modifyElement: (_ element: inout Element) -> ()) {
var element = self[index]
modifyElement(&element)
self[index] = element
}
}
Example usage:
testings.modifyElement(atIndex: 0) { $0.value = 99 }
testings.modifyForEach { $1.value *= 2 }
testings.modifyForEach { $1.value = $0 }
How to change Array of Structs
for every element:
itemsArray.indices.forEach { itemsArray[$0].someValue = newValue }
for specific element:
itemsArray.indices.filter { itemsArray[$0].propertyToCompare == true }
.forEach { itemsArray[$0].someValue = newValue }
You have enough of good answers. I'll just tackle the question from a more generic angle.
As another example to better understand value types and what it means they get copied:
struct Item {
var value:Int
}
func change (item: Item, with value: Int){
item.value = value // cannot assign to property: 'item' is a 'let' constant
}
That is because item is copied, when it comes in, it is immutable — as a convenience.
Had you made Item a class type then you were able to change its value.
var item2 = item1 // mutable COPY created
item2.value = 10
print(item2.value) // 10
print(item1.value) // 5
This is very tricky answer. I think, You should not do like this:
struct testing {
var value:Int
}
var test1 = testing(value: 6)
var test2 = testing(value: 12)
var ary = [UnsafeMutablePointer<testing>].convertFromArrayLiteral(&test1, &test2)
for p in ary {
p.memory.value = 3
}
if test1.value == test2.value {
println("value: \(test1.value)")
}
For Xcode 6.1, array initialization will be
var ary = [UnsafeMutablePointer<testing>](arrayLiteral: &test1, &test2)
It is possible to use the map function to get this effect - essentially creating a new array
itemsArray = itemsArray.map {
var card = $0
card.isDefault = aCard.token == token
return card
}
I ended up recreating a new array of struct see the example below.
func updateDefaultCreditCard(token: String) {
var updatedArray: [CreditCard] = []
for aCard in self.creditcards {
var card = aCard
card.isDefault = aCard.token == token
updatedArray.append(card)
}
self.creditcards = updatedArray
}
I tried Antonio's answer which seemed quite logical but to my surprise it does not work. Exploring this further I tried the following:
struct testing {
var value:Int
}
var test1 = testing(value: 6 )
var test2 = testing(value: 12 )
var testings = [ test1, test2 ]
var test1b = testings[0]
test1b.value = 13
// I would assume this is same as test1, but it is not test1.value is still 6
// even trying
testings[0].value = 23
// still the value of test1 did not change.
// so I think the only way is to change the whole of test1
test1 = test1b