NEW! Master Swift design patterns with my latest book! >>

How to shuffle an array in iOS 8 and below

Paul Hudson       @twostraws

Nate Cook wrote a simple shuffle() extension to arrays that implements the Fisher-Yates shuffle algorithm in Swift. I use it a lot, or at least did until GameplayKit came along in iOS 9.0 – it has its own shuffle algorithm, and so is preferable.

If you're stuck on iOS 8.0 or below, here's the code:

extension Array {
    mutating func shuffle() {
        for i in 0 ..< (count - 1) {
            let j = Int(arc4random_uniform(UInt32(count - i))) + i
            swapAt(i, j)
        }
    }
}

Available from iOS 2.0 – 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.

Swift on the server is here

Get ahead of the game and learn server-side Swift with my latest book – build real-world projects while you learn!

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>