SALE: Save 50% on all my books and bundles >>

What is class inheritance?

Swift version: 5.1

Paul Hudson    @twostraws   

Swift allows you to define a custom class as inheriting from another, which means it gains the functionality of the original class while being able to add its own. This is used extensively on Apple platforms: UIButton inherits from UIControl, which inherits from UIView, which inherits from UIResponder, which inherits from NSObject, for example.

This approach allows you to create something new by building upon and tweaking existing functionality. If you want to create a custom view for your app, you don’t need to go all the way back to basics – you can just inherit from UIView and make whatever changes you need. This means you automatically benefit from things like background colors, Auto Layout, CALayer, and more.

While inheritance is both power and used extensively, it does create some problems. The main two are first that it’s available only with classes and so Swift’s structs and enums are excluded, and the second are that it creates tight coupling, where one piece of code depends heavily on another piece of code.

Hacking with Swift is sponsored by Instabug

SPONSORED Catch bugs as soon as they happen and know exactly why a crash occurred by integrating Instabug's SDK in one minute. You will automatically receive device data, network logs, and reproduction steps with every bug and crash report.

Learn more and get started for free

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

Snapthread is a casual video editor and slideshow maker that makes discovering, compiling and sharing your favorite memories effortless.

Available from iOS 8.0

Similar solutions…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

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!