Written by Paul Hudson @twostraws
iOS 9.0 has a built-in way to shuffle arrays thanks to GameplayKit, and it's a simple one-liner. Here's an example of creating an array of lottery balls and picking six random ones:
let lotteryBalls = [Int](1...49)
let shuffledBalls = GKRandomSource.sharedRandom().arrayByShufflingObjects(in: lotteryBalls)
print(shuffledBalls[0])
print(shuffledBalls[1])
print(shuffledBalls[2])
print(shuffledBalls[3])
print(shuffledBalls[4])
print(shuffledBalls[5])That uses the system's built-in random number generator, which means it's guaranteed to be in a random state by the time it gets to you.
Available from iOS 9.0 – see Hacking with Swift tutorial 35
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