NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

How to generate a random number

Swift version: 5.2

Paul Hudson    @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.

Hacking with Swift is sponsored by Instabug

SPONSORED Are you tired of wasting time debugging your Swift app? Instabug’s SDK is here to help you minimize debugging time by providing you with complete device details, network logs, and reproduction steps with every bug report. All data is attached automatically, and it only takes a line of code to setup. Start your free trial now and get 3 months off exclusively for the Hacking with Swift Community.

Start your free trial!

Sponsor Hacking with Swift and reach the world's largest Swift community!

Available from iOS 8.0 – see Hacking with Swift tutorial 35

Similar solutions…

About the Swift Knowledge Base

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

BUY OUR BOOKS
Buy Pro Swift Buy Swift Design Patterns Buy Testing Swift Buy Hacking with iOS Buy Swift Coding Challenges Buy Swift on Sundays Volume One Buy Server-Side Swift (Vapor Edition) Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Advanced iOS Volume Three Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with macOS Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Server-Side Swift (Kitura Edition) Buy Beyond Code

Was this page useful? Let us know!

Average rating: 4.9/5

Link copied to your pasteboard.