A so-called “fair” random number generator is one that generates each of its possible values in equal amounts and with an even distribution. For example, if you were generating numbers between 1 and 4, you might get 4, 2, 1, 3, but you would never get 4 4 1 4.
GameplayKit has support for fair random number generation using
GKShuffledDistribution. First, add an import for the GameplayKit framework:
Second, create an instance of
GKShuffledDistribution, telling it the lowest and highest values it can generate:
let distribution = GKShuffledDistribution(lowestValue: 1, highestValue: 8)
nextInt() on it as needed to generate numbers. You should get all numbers between 1 and 8 at least once before you see any repeated.
Available from iOS 9.0 – see Hacking with Swift tutorial 35
Did this solution work for you? Please pass it on!
Other people are reading…
About the Swift Knowledge Base
This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.
Need to know Objective-C fast?
I wrote a book dedicated to teaching Objective-C to developers who already know Swift – it's the fastest way to get up to speed!