What are all the app lifecycle states in flutter ?

App Lifecycle States in Flutter

AppLifecycleState defines the state of the application:

States

resumed

App is visible and accepting user input (foreground).

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if (state == AppLifecycleState.resumed) {
  // Resume timers, API calls, animations
  startTimer();
}

inactive

App is visible but not accepting input (iOS only, when another app is displayed over it).

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if (state == AppLifecycleState.inactive) {
  // Pause animations, heavy operations
  pauseAnimation();
}

paused

App is not visible (background, locked screen, another app in foreground).

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if (state == AppLifecycleState.paused) {
  // Pause everything, save state
  saveState();
  pauseAudio();
}

detached

App is about to be terminated (rare, usually not used).

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if (state == AppLifecycleState.detached) {
  // Final cleanup
  cleanup();
}

Implementation

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class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> with WidgetsBindingObserver {
  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print('Lifecycle: $state');
    switch (state) {
      case AppLifecycleState.resumed:
        print('App resumed');
        break;
      case AppLifecycleState.inactive:
        print('App inactive');
        break;
      case AppLifecycleState.paused:
        print('App paused');
        break;
      case AppLifecycleState.detached:
        print('App detached');
        break;
    }
  }

  @override
  void dispose() {
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  Widget build(BuildContext context) => MaterialApp(home: HomeScreen());
}

Lifecycle Flow

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App Starts: resumed
  ↓
Press Home/Another App: inactive → paused
  ↓
Switch Back to App: resumed
  ↓
Close App: detached

Use Case: Save data on pause, resume timers on resume.