NEW: Learn SwiftUI with my free YouTube video series! >>

< Previous: Creating basic closures   Next: Returning values from a closure >

Accepting parameters in a closure

When you create closures, they don’t have a name or space to write any parameters. That doesn’t mean they can’t accept parameters, just that they do so in a different way: they are listed inside the open braces.

To make a closure accept parameters, list them inside parentheses just after the opening brace, then write in so that Swift knows the main body of the closure is starting.

For example, we could make a closure that accepts a place name string as its only parameter like this:

let driving = { (place: String) in
    print("I'm going to \(place) in my car")
}

One of the differences between functions and closures is that you don’t use parameter labels when running closures. So, to call driving() now we’d write this:

driving("London")

SPONSOR Meet the new Instabug – more than just bug reporting! We help you build better apps and minimize your debugging time. With each bug report, we automatically capture details like network requests, repro steps, and session details. Get real-time crash reports with stack trace details and session data to help you catch and fix issues easily. And with our customizable in-app surveys, you’ll gather insightful user feedback and much more. Instabug is the fastest and easiest way to release with confidence. Start your free trial now! Start your free trial now!

< Previous: Creating basic closures   Next: Returning values from a closure >
MASTER SWIFT NOW
Buy Testing Swift Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Advanced iOS Volume Two Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Average rating: 5.0/5

Click here to visit the Hacking with Swift store >>