NEW: My new book Pro SwiftUI is out now – level up your SwiftUI skills today! >>

Implicit returns from single-expression functions

Available from Swift 5.1

Paul Hudson      @twostraws

SE-0255 has removed a small but important inconsistency in the language: single-expression functions that return a value can now remove the return keyword and Swift will understand it implicitly.

In previous versions of Swift, single-line closures that returned a value you could omit the return keyword because the only line of code that was there must be the one that returned a value. So, these two pieces of code were identical:

let doubled1 = [1, 2, 3].map { $0 * 2 }
let doubled2 = [1, 2, 3].map { return $0 * 2 }

In Swift 5.1, this behavior has now been extended to functions as well: if they contain a single expression – effectively a single piece of code that evaluates to a value – then you can leave off the return keyword, like this:

func double(_ number: Int) -> Int {
    number * 2
}

That will probably cause some people to do a double take at first, but I’m sure it will become second nature over time.

Hacking with Swift is sponsored by Play

SPONSORED Play is the first native iOS design tool created for designers and engineers. You can install Play for iOS and iPad today and sign up to check out the Beta of our macOS app with SwiftUI code export. We're also hiring engineers!

Click to learn more about Play!

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

Other changes in Swift 5.1…

Download all Swift 5.1 changes as a playground Link to Swift 5.1 changes

Browse changes in all Swift versions

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.