NEW: My new book Pro SwiftUI is out now – level up your SwiftUI skills today! >>

What does the AppDelegate class do?

Swift version: 5.6

Paul Hudson    @twostraws   

If you create your app using one of Xcode’s built-in templates, you’ll automatically get an AppDelegate class in AppDelegate.swift, which comes with a handful of empty methods.

This class is supposed to be there to handle application lifecycle events - i.e., responding to the app being launched, backgrounded, foregrounded, receiving data, and so on. However, in practice AppDelegate is often abused as an easy dumping group for shared data – any thing that is used in several view controllers often gets thrown into the app delegate, but that’s nearly always the wrong place for it.

You may also sometimes see folks creating their initial user interface inside AppDelegate. This is broadly a bad idea unless you’re just starting out – if you’ve done this, consider splitting off that layout code either into a coordinator or into a view containment subclass.

Hacking with Swift is sponsored by RevenueCat

SPONSORED In-app subscriptions are a pain to implement, hard to test, and full of edge cases. RevenueCat makes it straightforward and reliable so you can get back to building your app. Oh, and it's free if your app makes less than $10k/mo.

Learn more

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

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 Pro SwiftUI 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 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 Beyond Code

Was this page useful? Let us know!

Average rating: 3.7/5

 
Unknown user

You are not logged in

Log in or create account
 

Link copied to your pasteboard.