How to generate a random number

Paul Hudson    September 2nd 2018    @twostraws

You can generate random numbers by calling the random() method on whatever numeric type you’re using, providing the range you want to work with. For example, this generates a random number in the range 1 through 5, inclusive on both sides:

let randomInt = Int.random(in: 1...5)

Similar methods exist for Double, Float, and CGFloat:

let randomDouble = Double.random(in: 1...100)
let randomFloat = Float.random(in: 1..<10)
let randomCGFloat = CGFloat.random(in: 1...1000)

There’s also one for booleans, generating true or false randomly:

let randomBool = Bool.random()

Checking a random boolean is effectively the same as checking Int.random(in: 0...1) == 1, but it helps clarify your intent.

Available from iOS 8.0 – see Hacking with Swift tutorial 35

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This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.