RandomArrays: pick randomly to build new array in two different ways

RandomArray.swift

//
// Description: RandomArrays: pick randomly to build new array in two different ways. One a shuffle the other 
// picking from the array. Shuffle uses Fischer-Yates algorithm to generate uniform randomness. Allthough it 
// might be better to use Apple's Game kit function GKRandomSource.sharedRandom().arrayByShufflingObjectsInArray(array)
// if available in the OS release. Also this only works on arrays, if you want to shuffle any colletion type 
// it is possible to extend MutableCollectionType. 
//
// Author: Paul Ossenbruggen
//
// Date: Nov 20, 2015
// Language: Swift
//


import Foundation

// picks only numbers from array may pick same values over and over.
let array = [10, 4, 2, 5, 6, 3, 1, 14, 11, 15]
print(array.map { _ in
    return array[Int(arc4random_uniform(UInt32(array.count)))]
})

func shuffleArray(var array : [Int]) -> [Int] {
    for (index, _) in array[0..<array.count-1].enumerate() {
        let randomIndex = Int(arc4random_uniform(UInt32(array.count - index))) + index
        guard index != randomIndex else { continue } // swap does not like it if you swap same indexes
        swap(&array[index], &array[randomIndex])
    }
    return array
}

print(shuffleArray(array))
print(array) // swift does not change original array.


func shuffleArrayInPlace(inout array : [Int]) {
    for (index, _) in array[0..<array.count-1].enumerate() {
        let randomIndex = Int(arc4random_uniform(UInt32(array.count - index))) + index
        guard index != randomIndex else { continue } // swap does not like it if you swap same indexes
        swap(&array[index], &array[randomIndex])
    }
}

var newArray = array
shuffleArrayInPlace(&newArray)
print(newArray)