Describe the app and UIViewController lifecycle.

Junior PRO

The application

States: Not running → Inactive → Active → Background → Suspended. Since iOS 13 the foreground/background transitions belong to the scene (UIWindowSceneDelegate), while launch and system events go to UIApplicationDelegate:

• application(_:didFinishLaunchingWithOptions:) — the process started, set up services.
• scene(_:willConnectTo:options:) — create the UIWindow, handle a URL/push from connectionOptions.
• sceneWillEnterForeground → sceneDidBecomeActive — refresh data, resume work.
• sceneWillResignActive → sceneDidEnterBackground — pause, save state (the next step may be Suspended and eviction without callbacks).
• sceneDidDisconnect — the scene was closed (a window on iPad), release resources.

In SwiftUI the same phases are read through @Environment(\.scenePhase). Per TN3187, after iOS 26 apps without scenes will not launch.