NEW: Learn to build amazing SwiftUI apps for macOS with my new book! >>

More keywords can be used as argument labels

Available from Swift 2.2

Paul Hudson      @twostraws

Argument labels are a core feature of Swift, and let us write code like this:

for i in 1.stride(through: 9, by: 2) {

Without the through or by labels, this code would lose its self-documenting nature: what do the 9 and 2 do in 1.stride(9, 2)? In this example, Swift also uses the argument labels to distinguish 1.stride(through: 9, by: 2) from 1.stride(to: 9, by: 2), which produces different results.

As of Swift 2.2, you can now use a variety of language keywords as these argument labels. You might wonder why this would be a good thing, but consider this code:

func printGreeting(name: String, repeat repeatCount: Int) {
    for _ in 0 ..< repeatCount {

printGreeting("Taylor", repeat: 5)

That uses repeat as an argument label, which makes sense because the function will print a string a number of times. Because repeat is a keyword, this code would not work before Swift 2.2 – you would need to write repeat instead, which is unpleasant.

Note that there are still some keywords that may not be used, specifically var, let and inout.

Hacking with Swift is sponsored by RevenueCat

SPONSORED Spend less time managing in-app purchase infrastructure so you can focus on building your app. RevenueCat gives everything you need to easily implement, manage, and analyze in-app purchases and subscriptions without managing servers or writing backend code.

Get Started

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

Other changes in Swift 2.2…

Download all Swift 2.2 changes as a playground Link to Swift 2.2 changes

Browse changes in all Swift versions

Unknown user

You are not logged in

Log in or create account

Link copied to your pasteboard.