Bye Bye AppDelegate! SwiftUI App Life Cycle

Photo by Maxwell Nelson on Unsplash

Now XCode 12 introduces two options for app life cycle. When you create new project by xcode then you can see Life Cycle dropdown to choose.

UIKit AppDelegate or SwiftUI

XCode 12 — Choose project template

Get Started

Once you create a project with the above setting, you project in xcode will look like this:

Default SwiftUI life cycle

You can see that there are two swift files — one SwiftUILifeCycleAppApp.swift & ContentView.swift

ContentView.swift is the first view file which renders on the window where SwiftUILifeCycleAppApp.swift is your main entry point in the app just like AppDelegate.

Let’s dive into depth of SwiftUILifeCycleAppApp.swift

There is a struct ‘SwiftUILifeCycleAppApp’ which confirms to App protocol and in the body part, ContentView is added on the app Window. That’s it, nothing else in the file. You can see, it is so light weighted. One more thing, you can see @main just above the struct ‘SwiftUILifeCycleAppApp’. It tells…