SALE: Save 50% on all my books and bundles >>

How to convert a String to an Int

Swift version: 5.1

Paul Hudson    @twostraws   

If you have an integer hiding inside a string, you can convert between the two just by using the integer's initializer, like this:

let myString1 = "556"
let myInt1 = Int(myString1)

Because strings might contain something that isn’t a number – e.g. “Fish” rather than “556” – the Int initializer will return an optional integer, so if you want to force a value you should use nil coalescing like this:

let myInt2 = Int(myString) ?? 0

That means “attempt to convert myString to an integer, but if the conversion failed because it contained something invalid then use 0 instead.”

As with other data types (Float and Double) it’s also possible to convert by using NSString if you’re desperate:

let myInt3 = (myString1 as NSString).integerValue

Ideally, though, that shouldn’t needed.

Hacking with Swift is sponsored by RevenueCat

SPONSORED Building in-app subscriptions are hard. RevenueCat makes it simple. With their open source SDKs, you can painlessly implement subscriptions for your app in hours, not months.

Explore the docs to learn more

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

Snapthread is a casual video editor and slideshow maker that makes discovering, compiling and sharing your favorite memories effortless.

Available from iOS 7.0

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: 4.4/5