NEW: Subscribe to Hacking with Swift+ and accelerate your learning! >>

Default parameters

The print() function prints something to the screen, but always adds a new line to the end of whatever you printed, so that multiple calls to print() don’t all appear on the same line.

You can change that behavior if you want, so you could use spaces rather than line breaks. Most of the time, though, folks want new lines, so print() has a terminator parameter that uses new line as its default value.

You can give your own parameters a default value just by writing an = after its type followed by the default you want to give it. So, we could write a greet() function that can optionally print nice greetings:

func greet(_ person: String, nicely: Bool = true) {
    if nicely == true {
        print("Hello, \(person)!")
    } else {
        print("Oh no, it's \(person) again...")
    }
}

That can be called in two ways:

greet("Taylor")
greet("Taylor", nicely: false)
Hacking with Swift is sponsored by Fernando Olivares

SPONSORED Ever ask for help and your reviewer immediately notices issues you missed? Fernando Olivares is a 10-year veteran from Big Nerd Ranch and Lambda School who can help hone your app building skills, and he's just launched a new book that does just that – use the code "hacking" to save $5!

Buy the book

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: 4.4/5

Link copied to your pasteboard.