UPGRADE YOUR SKILLS: Learn advanced Swift and SwiftUI on Hacking with Swift+! >>

How to break out of multiple loop levels using labeled statements

Swift version: 5.6

Paul Hudson    @twostraws   

Swift has a built-in break keyword that escapes the current loop you’re in, but what happens if you’re in two loops or more and want to break out of them all?

Swift’s labeled statements are designed to solve this problem: they let you exit any number of loops or conditions, so execution picks up directly after the block you labeled.

For example, consider this pair of loops that will find the first number that, when squared, makes 144:

let numbers = 1...100

for number1 in numbers {
    for number2 in numbers {
        if number1 == number2 && number1 * number2 == 144 {
            print("Square found: \(number1)")

As soon as we’ve found that square, we can stop looking. The problem is, a regular break won’t work here because it will exit only the inner loop – the outer loop will keep counting 13, 14, 15, and so on up to 100. However, if we add a label to the outer loop we can break out of both loops at once, like this:

outerLoop: for number1 in numbers {
    for number2 in numbers {
        if number1 == number2 && number1 * number2 == 144 {
            print("Square found: \(number1)")
            break outerLoop

Notice the outerLoop: before the for number1 loop, and also the matching break outerLoop – that will cause both loops to exit as soon as the correct number is found.

Hacking with Swift is sponsored by RevenueCat

SPONSORED Take the pain out of configuring and testing your paywalls. RevenueCat's Paywalls allow you to remotely configure your entire paywall view without any code changes or app updates.

Learn more here

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

Available from iOS 8.0 – learn more in my book Pro Swift

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 Pro Swift Buy Pro SwiftUI 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 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 Beyond Code

Was this page useful? Let us know!

Average rating: 5.0/5

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.