重复Lucas所说的，你可以像这样创建Array类的扩展:

extension Array {
    func randomItem() -> Element? {
        if isEmpty { return nil }
        let index = Int(arc4random_uniform(UInt32(self.count)))
        return self[index]
    }
}

例如:

let myArray = [1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16]
let myItem = myArray.randomItem() // Note: myItem is an Optional<Int>

检查空数组的替代功能实现。

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])

如果你想要获得多个随机元素从你的数组没有重复，GameplayKit有你覆盖:

import GameplayKit
let array = ["one", "two", "three", "four"]

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

let firstRandom = shuffled[0]
let secondRandom = shuffled[1]

你有两个选择的随机性，见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.

跟随其他人的回答，但有Swift 2支持。

快1.倍

extension Array {
    func sample() -> T {
        let index = Int(arc4random_uniform(UInt32(self.count)))
        return self[index]
    }
}

快2.倍

extension Array {
    func sample() -> Element {
        let index = Int(arc4random_uniform(UInt32(self.count)))
        return self[index]
    }
}

例如:

let arr = [2, 3, 5, 7, 9, 11, 13, 17, 19, 23, 29, 31]
let randomSample = arr.sample()

你可以使用Swift内置的random()函数以及扩展:

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

斯威夫特3

进口GameKit

func getRandomMessage() -> String {

    let messages = ["one", "two", "three"]

    let randomNumber = GKRandomSource.sharedRandom().nextInt(upperBound: messages.count)

    return messages[randomNumber].description

}