NEW: Start my new Ultimate Portfolio App course with a free Hacking with Swift+ trial! >>

Omitting parameter labels

You might have noticed that we don’t actually send any parameter names when we call print() – we say print("Hello") rather than print(message: "Hello").

You can get this same behavior in your own functions by using an underscore, _, for your external parameter name, like this:

func greet(_ person: String) {
    print("Hello, \(person)!")
}

You can now call greet() without having to use the person parameter name:

greet("Taylor")

This can make some code more natural to read, but generally it’s better to give your parameters external names to avoid confusion. For example, if I say setAlarm(5) it’s hard to tell what that means – does it set an alarm for five o’clock, set an alarm for five hours from now, or activate pre-configured alarm number 5?

Hacking with Swift is sponsored by ViRE

SPONSORED ViRE offers discoverable way of working with regex. It provides really readable regex experience, code complete & cheat sheet, unit tests, powerful replace system, step-by-step search & replace, regex visual scheme, regex history & playground. ViRE is available on Mac & iPad.

Download on the App Store

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

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

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.