Swift 4.2 +

Question

如何在Swift中随机化或随机播放数组中的元素？例如，如果我的阵列由52张扑克牌组成，我想随机播放阵列以便改组牌组。

Answer 1

这个答案详细说明了如何在Swift 4.2+中使用快速统一的算法（Fisher-Yates），以及如何在各种先前版本的Swift中添加相同的功能。每个Swift版本的命名和行为都与该版本的变异和非变异排序方法相匹配。

Swift 4.2 +

shuffle和shuffled是原生的Swift 4.2。用法示例：

let x = [1, 2, 3].shuffled()
// x == [2, 3, 1]

let fiveStrings = stride(from: 0, through: 100, by: 5).map(String.init).shuffled()
// fiveStrings == ["20", "45", "70", "30", ...]

var numbers = [1, 2, 3, 4]
numbers.shuffle()
// numbers == [3, 2, 1, 4]

Swift 4.0和4.1

这些扩展为任何可变集合（数组和不安全的可变缓冲区）添加shuffle()方法，并为任何序列添加shuffled()方法：

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)) {
            // Change `Int` in the next line to `IndexDistance` in < Swift 4.1
            let d: Int = 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
    }
}

与上面的Swift 4.2示例中的用法相同。

Swift 3

这些扩展为任何可变集合添加shuffle()方法，并为任何序列添加shuffled()方法：

extension MutableCollection where Indices.Iterator.Element == Index {
    /// 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)) {
            // Change `Int` in the next line to `IndexDistance` in < Swift 3.2
            let d: Int = numericCast(arc4random_uniform(numericCast(unshuffledCount)))
            guard d != 0 else { continue }
            let i = index(firstUnshuffled, offsetBy: d)
            self.swapAt(firstUnshuffled, i)
        }
    }
}

extension Sequence {
    /// Returns an array with the contents of this sequence, shuffled.
    func shuffled() -> [Iterator.Element] {
        var result = Array(self)
        result.shuffle()
        return result
    }
}

与上面的Swift 4.2示例中的用法相同。

Swift 2

（过时的语言：从2018年7月起，您无法使用Swift 2.x在iTunes Connect上发布）

extension MutableCollectionType where Index == Int {
    /// Shuffle the elements of `self` in-place.
    mutating func shuffleInPlace() {
        // empty and single-element collections don't shuffle
        if count < 2 { return }

        for i in startIndex ..< endIndex - 1 {
            let j = Int(arc4random_uniform(UInt32(count - i))) + i
            guard i != j else { continue }
            swap(&self[i], &self[j])
        }
    }
}

extension CollectionType {
    /// Return a copy of `self` with its elements shuffled.
    func shuffle() -> [Generator.Element] {
        var list = Array(self)
        list.shuffleInPlace()
        return list
    }
}

用法：

[1, 2, 3].shuffle()
// [2, 3, 1]

let fiveStrings = 0.stride(through: 100, by: 5).map(String.init).shuffle()
// ["20", "45", "70", "30", ...]

var numbers = [1, 2, 3, 4]
numbers.shuffleInPlace()
// [3, 2, 1, 4]

Swift 1.2

（过时的语言：从2018年7月开始，你不能使用Swift 1.x在iTunes Connect上发布）

`shuffle`作为变异数组方法

此扩展程序可让您将可变Array实例随机播放：

extension Array {
    mutating func shuffle() {
        if count < 2 { return }
        for i in 0..<(count - 1) {
            let j = Int(arc4random_uniform(UInt32(count - i))) + i
            swap(&self[i], &self[j])
        }
    }
}
var numbers = [1, 2, 3, 4, 5, 6, 7, 8]
numbers.shuffle()                     // e.g., numbers == [6, 1, 8, 3, 2, 4, 7, 5]

`shuffled`作为非变异数组方法

此扩展程序将允许您检索Array实例的随机副本：

extension Array {
    func shuffled() -> [T] {
        if count < 2 { return self }
        var list = self
        for i in 0..<(list.count - 1) {
            let j = Int(arc4random_uniform(UInt32(list.count - i))) + i
            swap(&list[i], &list[j])
        }
        return list
    }
}
let numbers = [1, 2, 3, 4, 5, 6, 7, 8]
let mixedup = numbers.shuffled()     // e.g., mixedup == [6, 1, 8, 3, 2, 4, 7, 5]

Answer 2

Edit: As noted in other answers, Swift 4.2 finally之间的“url”和“content”，将随机数生成添加到标准库中，完成数组重排。 / p>

但是，GameplayKit中的GKRandom / GKRandomDistribution套件对于新的RandomNumberGenerator协议仍然有用 - 如果您向GameplayKit RNG添加扩展以符合新的标准库协议，你可以很容易地得到：

可发送的RNG（可在需要进行测试时重现“随机”序列）
牺牲速度稳健性的RNG
产生非均匀分布的RNG

...并且仍然使用Swift中漂亮的新“本机”随机API。

本答案的其余部分涉及此类RNG和/或它们在较旧的Swift编译器中的使用。

这里已经有了一些很好的答案，以及一些很好的例子，说明如果你不小心的话，写你自己的shuffle可能容易出错。

在iOS 9，macOS 10.11和tvOS 9（或更高版本）中，您不必自己编写。 GameplayKit中有an efficient, correct implementation of Fisher-Yates（尽管有名称，但不仅仅是游戏）。

如果您只想要一个独特的随机播放：

let shuffled = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: array)

如果您希望能够复制shuffle或一系列shuffle，请选择并播种特定的随机源; e.g。

let lcg = GKLinearCongruentialRandomSource(seed: mySeedValue)
let shuffled = lcg.arrayByShufflingObjects(in: array)

在iOS 10 / macOS 10.12 / tvOS 10中，还有一种方便的语法可以通过NSArray上的扩展进行混洗。当然，当你使用Swift Array时它会有点麻烦（并且在返回Swift时它会丢失它的元素类型）：

let shuffled1 = (array as NSArray).shuffled(using: random) // -> [Any]
let shuffled2 = (array as NSArray).shuffled() // use default random source

但是为它制作一个保留类型的Swift包装器非常容易：

extension Array {
    func shuffled(using source: GKRandomSource) -> [Element] {
        return (self as NSArray).shuffled(using: source) as! [Element]
    }
    func shuffled() -> [Element] {
        return (self as NSArray).shuffled() as! [Element]
    }
}
let shuffled3 = array.shuffled(using: random)
let shuffled4 = array.shuffled()

Answer 3

在 Swift 2.0 中，GameplayKit可能会来救援！（由 iOS9 或更高版本支持）

import GameplayKit

func shuffle() {
    array = GKRandomSource.sharedRandom().arrayByShufflingObjectsInArray(array)
}

Answer 4

这可能有点短：

sorted(a) {_, _ in arc4random() % 2 == 0}

Answer 5

采用Nate's算法我想看看Swift 2和协议扩展的外观。

这就是我想出来的。

extension MutableCollectionType where Self.Index == Int {
    mutating func shuffleInPlace() {
        let c = self.count
        for i in 0..<(c - 1) {
            let j = Int(arc4random_uniform(UInt32(c - i))) + i
            swap(&self[i], &self[j])
        }
    }
}

extension MutableCollectionType where Self.Index == Int {
    func shuffle() -> Self {
        var r = self
        let c = self.count
        for i in 0..<(c - 1) {
            let j = Int(arc4random_uniform(UInt32(c - i))) + i
            swap(&r[i], &r[j])
        }
        return r
    }
}

现在，任何MutableCollectionType都可以使用这些方法，因为它使用Int作为Index

Answer 6

就我而言，我遇到了在Array中交换对象的一些问题。然后我挠挠头去重新发明轮子。

// swift 3.0 ready
extension Array {

    func shuffled() -> [Element] {
        var results = [Element]()
        var indexes = (0 ..< count).map { $0 }
        while indexes.count > 0 {
            let indexOfIndexes = Int(arc4random_uniform(UInt32(indexes.count)))
            let index = indexes[indexOfIndexes]
            results.append(self[index])
            indexes.remove(at: indexOfIndexes)
        }
        return results
    }

}

Answer 7

这是 Swift 4 的Nate's implementation of the Fisher-Yates shuffle版本（Xcode 9）。

extension MutableCollection {
    /// Shuffle the elements of `self` in-place.
    mutating func shuffle() {
        for i in indices.dropLast() {
            let diff = distance(from: i, to: endIndex)
            let j = index(i, offsetBy: numericCast(arc4random_uniform(numericCast(diff))))
            swapAt(i, j)
        }
    }
}

extension Collection {
    /// Return a copy of `self` with its elements shuffled
    func shuffled() -> [Element] {
        var list = Array(self)
        list.shuffle()
        return list
    }
}

变化是：

约束Indices.Iterator.Element == Index现在已成为其中的一部分 Collection协议，不需要强制执行延伸了。
交换元素必须通过调用集合上的swapAt()来完成，比较SE-0173 Add MutableCollection.swapAt(_:_:)。
Element是Iterator.Element的别名。

Answer 8

这就是我使用的：

func newShuffledArray(array:NSArray) -> NSArray {
    var mutableArray = array.mutableCopy() as! NSMutableArray
    var count = mutableArray.count
    if count>1 {
        for var i=count-1;i>0;--i{
            mutableArray.exchangeObjectAtIndex(i, withObjectAtIndex: Int(arc4random_uniform(UInt32(i+1))))
        }
    }
    return mutableArray as NSArray
}

Answer 9

Swift 4 在for循环中对数组的元素进行混洗，其中i是混合比率

var cards = [Int]() //Some Array
let i = 4 // is the mixing ratio
func shuffleCards() {
    for _ in 0 ..< cards.count * i {
        let card = cards.remove(at: Int(arc4random_uniform(UInt32(cards.count))))
        cards.insert(card, at: Int(arc4random_uniform(UInt32(cards.count))))
    }
}

或者使用扩展名Int

func shuffleCards() {
    for _ in 0 ..< cards.count * i {
        let card = cards.remove(at: cards.count.arc4random)
        cards.insert(card, at: cards.count.arc4random)
    }
}
extension Int {
    var arc4random: Int {
        if self > 0 {
            print("Arc for random positiv self \(Int(arc4random_uniform(UInt32(self))))")
        return Int(arc4random_uniform(UInt32(self)))
        } else if self < 0 {
            print("Arc for random negotiv self \(-Int(arc4random_uniform(UInt32(abs(self)))))")
            return -Int(arc4random_uniform(UInt32(abs(self))))
        } else {
            print("Arc for random equal 0")
            return 0
        }
    }
}

Answer 10

使用Swift 3，如果你想在一个位置改组数组或从数组中获取一个新的混洗数组，AnyIterator可以帮助你。我们的想法是从您的数组创建索引数组，使用AnyIterator实例和swap(_:_:)函数对这些索引进行洗牌，并将此AnyIterator实例的每个元素映射到数组＆＃39 ; s相应的元素。

以下Playground代码显示了它的工作原理：

import Darwin // required for arc4random_uniform

let array = ["Jock", "Ellie", "Sue Ellen", "Bobby", "JR", "Pamela"]
var indexArray = Array(array.indices)
var index = indexArray.endIndex

let indexIterator: AnyIterator<Int> = AnyIterator {
    guard let nextIndex = indexArray.index(index, offsetBy: -1, limitedBy: indexArray.startIndex)
        else { return nil }

    index = nextIndex
    let randomIndex = Int(arc4random_uniform(UInt32(index)))
    if randomIndex != index {
        swap(&indexArray[randomIndex], &indexArray[index])
    }

    return indexArray[index]
}

let newArray = indexIterator.map { array[$0] }
print(newArray) // may print: ["Jock", "Ellie", "Sue Ellen", "JR", "Pamela", "Bobby"]

您可以重构前面的代码并在shuffled()扩展名中创建Array函数，以便从数组中获取新的随机数组：

import Darwin // required for arc4random_uniform

extension Array {

    func shuffled() -> Array<Element> {
        var indexArray = Array<Int>(indices)        
        var index = indexArray.endIndex

        let indexIterator = AnyIterator<Int> {
            guard let nextIndex = indexArray.index(index, offsetBy: -1, limitedBy: indexArray.startIndex)
                else { return nil }

            index = nextIndex                
            let randomIndex = Int(arc4random_uniform(UInt32(index)))
            if randomIndex != index {
                swap(&indexArray[randomIndex], &indexArray[index])
            }

            return indexArray[index]
        }

        return indexIterator.map { self[$0] }
    }

}

用法：

let array = ["Jock", "Ellie", "Sue Ellen", "Bobby", "JR", "Pamela"]
let newArray = array.shuffled()
print(newArray) // may print: ["Bobby", "Pamela", "Jock", "Ellie", "JR", "Sue Ellen"]

let emptyArray = [String]()
let newEmptyArray = emptyArray.shuffled()
print(newEmptyArray) // prints: []

作为上一代码的替代方法，您可以在shuffle()扩展程序中创建Array函数，以便对阵列进行随机播放：

import Darwin // required for arc4random_uniform

extension Array {

    mutating func shuffle() {
        var indexArray = Array<Int>(indices)
        var index = indexArray.endIndex

        let indexIterator = AnyIterator<Int> {
            guard let nextIndex = indexArray.index(index, offsetBy: -1, limitedBy: indexArray.startIndex)
                else { return nil }

            index = nextIndex                
            let randomIndex = Int(arc4random_uniform(UInt32(index)))
            if randomIndex != index {
                swap(&indexArray[randomIndex], &indexArray[index])
            }

            return indexArray[index]
        }

        self = indexIterator.map { self[$0] }
    }

}

用法：

var mutatingArray = ["Jock", "Ellie", "Sue Ellen", "Bobby", "JR", "Pamela"]
mutatingArray.shuffle()
print(mutatingArray) // may print ["Sue Ellen", "Pamela", "Jock", "Ellie", "Bobby", "JR"]

Answer 11

Swift 3解决方案，在@Nate Cook回答:(如果索引从0开始工作，请参阅下面的评论）

extension Collection {
    /// Return a copy of `self` with its elements shuffled
    func shuffle() -> [Generator.Element] {
        var list = Array(self)
        list.shuffleInPlace()
        return list
    } }

extension MutableCollection where Index == Int {
    /// Shuffle the elements of `self` in-place.
    mutating func shuffleInPlace() {
        // empty and single-element collections don't shuffle
        if count < 2 { return }
        let countInt = count as! Int

    for i in 0..<countInt - 1 {
        let j = Int(arc4random_uniform(UInt32(countInt - i))) + i
            guard i != j else { continue }
            swap(&self[i], &self[j])
        }
    }
}

Answer 12

这是以最简单的方式完成的。import Gamplaykit到你的VC并使用下面的代码。在Xcode 8中测试。

 import GameplayKit

 let array: NSArray = ["Jock", "Ellie", "Sue Ellen", "Bobby", "JR", "Pamela"]

 override func viewDidLoad() {
    super.viewDidLoad()

    print(array.shuffled())  
}

如果你想从数组中获取一个混洗的字符串，你可以使用下面的代码..

func suffleString() {

    let ShuffleArray = array.shuffled()

    suffleString.text = ShuffleArray.first as? String

    print(suffleString.text!)

}

Answer 13

您也可以使用通用swap函数并实现提到的Fisher-Yates：

for idx in 0..<arr.count {
  let rnd = Int(arc4random_uniform(UInt32(idx)))
  if rnd != idx {
    swap(&arr[idx], &arr[rnd])
  }
}

或更简洁：

for idx in 0..<steps.count {
  swap(&steps[idx], &steps[Int(arc4random_uniform(UInt32(idx)))])
}

Answer 14

在 Swift 4.2 中，现在有mutable shuffle和immutable shuffled的方法。您可以阅读有关随机生成和数组内容here的更多信息。

Answer 15

作品！。有机体是洗牌的阵列。

extension Array
{
    /** Randomizes the order of an array's elements. */
    mutating func shuffle()
    {
        for _ in 0..<10
        {
            sort { (_,_) in arc4random() < arc4random() }
        }
    }
}

var organisms = [
    "ant",  "bacteria", "cougar",
    "dog",  "elephant", "firefly",
    "goat", "hedgehog", "iguana"]

print("Original: \(organisms)")

organisms.shuffle()

print("Shuffled: \(organisms)")

Answer 16

从Swift 4.2开始，有两个方便的功能：

// shuffles the array in place
myArray.shuffle()

和

// generates a new array with shuffled elements of the old array
let newArray = myArray.shuffled()

Answer 17

如果要使用简单的Swift For循环功能，请使用此->

var arrayItems = ["A1", "B2", "C3", "D4", "E5", "F6", "G7", "H8", "X9", "Y10", "Z11"]
var shuffledArray = [String]()

for i in 0..<arrayItems.count
{
    let randomObject = Int(arc4random_uniform(UInt32(items.count)))

    shuffledArray.append(items[randomObject])

    items.remove(at: randomObject)
}

print(shuffledArray)

使用扩展名->

的Swift Array Slack

extension Array {
    // Order Randomize
    mutating func shuffle() {
        for _ in 0..<count {
            sort { (_,_) in arc4random() < arc4random() }
        }
    }
}

Answer 18

在SWIFT 4中

func createShuffledSequenceOfNumbers(max:UInt)->[UInt] {

    var array:[UInt]! = []
    var myArray:[UInt]! = []
    for i in 1...max {
        myArray.append(i)
    }
    for i in 1...max {
        array.append(i)
    }
    var tempArray:[Int]! = []
    for index in 0...(myArray.count - 1) {

        var isNotFinded:Bool = true
        while(isNotFinded){

            let randomNumber = arc4random_uniform(UInt32(myArray.count))
            let randomIndex = Int(randomNumber)

            if(!tempArray.contains(randomIndex)){
                tempArray.append(randomIndex)

                array[randomIndex] = myArray[index]
                isNotFinded = false
            }
        }
    }

    return array
}

Answer 19

工作阵列扩展（变异和非变异）

Swift 4.1 / Xcode 9

最常见的答案已被弃用，所以我自己创建了自己的扩展来在最新版本的Swift，Swift 4.1（Xcode 9）中随机播放一个数组：

extension Array {

// Non-mutating shuffle
    var shuffled : Array {
        let totalCount : Int = self.count
        var shuffledArray : Array = []
        var count : Int = totalCount
        var tempArray : Array = self
        for _ in 0..<totalCount {
            let randomIndex : Int = Int(arc4random_uniform(UInt32(count)))
            let randomElement : Element = tempArray.remove(at: randomIndex)
            shuffledArray.append(randomElement)
            count -= 1
        }
        return shuffledArray
    }

// Mutating shuffle
    mutating func shuffle() {
        let totalCount : Int = self.count
        var shuffledArray : Array = []
        var count : Int = totalCount
        var tempArray : Array = self
        for _ in 0..<totalCount {
            let randomIndex : Int = Int(arc4random_uniform(UInt32(count)))
            let randomElement : Element = tempArray.remove(at: randomIndex)
            shuffledArray.append(randomElement)
            count -= 1
        }
        self = shuffledArray
    }
}

调用非变异随机播放`[Array] -> [Array]`：

let array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

print(array.shuffled)

以随机顺序打印array。

调用Mutuff Shuffle `[Array] = [Array]`：

var array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]

array.shuffle() 
// The array has now been mutated and contains all of its initial 
// values, but in a randomized shuffled order

print(array)

以当前顺序打印array，该顺序已经随机洗牌。

希望这适用于所有人，如果您有任何问题，建议或意见，请随时提出！

Answer 20

简单示例：

extension Array {
    mutating func shuffled() {
        for _ in self {
            // generate random indexes that will be swapped
            var (a, b) = (Int(arc4random_uniform(UInt32(self.count - 1))), Int(arc4random_uniform(UInt32(self.count - 1))))
            if a == b { // if the same indexes are generated swap the first and last
                a = 0
                b = self.count - 1
            }
            swap(&self[a], &self[b])
        }
    }
}

var array = [1,2,3,4,5,6,7,8,9,10]
array.shuffled()
print(array) // [9, 8, 3, 5, 7, 6, 4, 2, 1, 10]

Answer 21

这就是我使用的：

import GameplayKit

extension Collection {
    func shuffled() -> [Iterator.Element] {
        let shuffledArray = (self as? NSArray)?.shuffled()
        let outputArray = shuffledArray as? [Iterator.Element]
        return outputArray ?? []
    }
    mutating func shuffle() {
        if let selfShuffled = self.shuffled() as? Self {
            self = selfShuffled
        }
    }
}

// Usage example:

var numbers = [1,2,3,4,5]
numbers.shuffle()

print(numbers) // output example: [2, 3, 5, 4, 1]

print([10, "hi", 9.0].shuffled()) // output example: [hi, 10, 9]

Answer 22

let shuffl = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: arrayObject)

Answer 23

这是如何在Swift 3.0中使用种子对一个数组进行混洗。

extension MutableCollection where Indices.Iterator.Element == Index {
    mutating func shuffle() {
        let c = count
        guard c > 1 else { return }


        for (firstUnshuffled , unshuffledCount) in zip(indices, stride(from: c, to: 1, by: -1)) {
            srand48(seedNumber)
            let number:Int = numericCast(unshuffledCount)
            let r = floor(drand48() * Double(number))

            let d: IndexDistance = numericCast(Int(r))
            guard d != 0 else { continue }
            let i = index(firstUnshuffled, offsetBy: d)
            swap(&self[firstUnshuffled], &self[i])
        }
    }
}

Answer 24

这里有一些在游乐场中运行的代码。您不需要在实际的Xcode项目中导入Darwin。

import darwin

var a = [1,2,3,4,5,6,7]

func shuffle<ItemType>(item1: ItemType, item2: ItemType) -> Bool {
    return drand48() > 0.5
}

sort(a, shuffle)

println(a)

Answer 25

当我将xCode版本升级到7.4 beta时，它停在“swap（＆amp; self [i]，＆amp; self [j]）”。致命错误：不支持自行交换位置

我发现i = j的原因（交换功能会爆炸）

所以我添加一个条件如下

if (i != j){
    swap(&list[i], &list[j])
}

YA！对我来说没关系。

如何在Swift中对数组进行洗牌？

25 个答案:

Swift 4.2 +

Swift 4.0和4.1

Swift 3

Swift 2

Swift 1.2

`shuffle`作为变异数组方法

`shuffled`作为非变异数组方法

工作阵列扩展（变异和非变异）

Swift 4.1 / Xcode 9

调用非变异随机播放`[Array] -> [Array]`：

调用Mutuff Shuffle `[Array] = [Array]`：

如何在Swift中对数组进行洗牌？

25 个答案:

Swift 4.2 +

Swift 4.0和4.1

Swift 3

Swift 2

Swift 1.2

shuffle作为变异数组方法

shuffled作为非变异数组方法

工作阵列扩展（变异和非变异）

Swift 4.1 / Xcode 9

调用非变异随机播放[Array] -> [Array]：

调用Mutuff Shuffle [Array] = [Array]：

`shuffle`作为变异数组方法

`shuffled`作为非变异数组方法

调用非变异随机播放`[Array] -> [Array]`：

调用Mutuff Shuffle `[Array] = [Array]`：