As far as I know, Xcode 13 has removed Life Cycle from templates of SwiftUI apps.
If you want a project template with Life Cycle as UIKit App Delegate,
create a project with Xcode 12
create a new SwiftUI project with Xcode 13 and create/copy AppDelegate.swift and SceneDelegate.swift by yourself
create a new UIKit project (Interface: Storyboard) with Xcode 13 and modify SceneDelegate.swift by yourself
(You may need to modify some settings.)
Check this similar thread of 3 months ago.
Topic:
Developer Tools & Services
SubTopic:
Xcode
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