.shuffle()和.shuffled()是Swift的一部分
原历史问题:
我如何随机或洗牌在Swift数组中的元素?例如，如果我的数组包含52张扑克牌，我想要洗牌数组以洗牌牌组。
当前回答
简单的例子:
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]
其他回答
在我的例子中，我在数组中交换对象时遇到了一些问题。然后我挠头，开始重新发明轮子。
// 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
}
}
这是我所使用的:
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]
这是最简单的方法。导入Gamplaykit到你的VC中，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得一个打乱的字符串，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!)
}
let shuffl = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: arrayObject)
你也可以使用通用交换函数，实现前面提到的Fisher-Yates:
for idx in 0..<arr.count {
let rnd = Int(arc4random_uniform(UInt32(idx)))
if rnd != idx {
swap(&arr[idx], &arr[rnd])
}
}
或者更简洁:
for idx in 0..<steps.count {
swap(&steps[idx], &steps[Int(arc4random_uniform(UInt32(idx)))])
}
