Articles, podcasts and news about Swift development, by John Sundell.

UIKit default arguments

Published on 11 Dec 2017

It's awesome that many UIKit APIs with completion handlers and other optional parameters import into Swift with default arguments (even though they are written in Objective-C). Getting rid of all those nil arguments is so nice!

// BEFORE: All parameters are specified, just like in Objective-C

viewController.present(modalViewController, animated: true, completion: nil)

modalViewController.dismiss(animated: true, completion: nil)

viewController.transition(from: loadingViewController,
                          to: contentViewController,
                          duration: 0.3,
                          options: [],
                          animations: animations,
                          completion: nil)

// AFTER: Since many UIKit APIs with completion handlers and other
// optional parameters import into Swift with default arguments,
// we can make our calls shorter

viewController.present(modalViewController, animated: true)

modalViewController.dismiss(animated: true)

viewController.transition(from: loadingViewController,
                          to: contentViewController,
                          duration: 0.3,
                          animations: animations)

Support Swift by Sundell by checking out this sponsor:

Essential Developer

Essential Developer: Learn the most up-to-date techniques and strategies for testing new and legacy Swift code in this free practical course for developers who want to become complete senior iOS developers. This virtual event includes lectures, mentoring sessions, and step-by-step instructions. Click to learn more.