> For the complete documentation index, see [llms.txt](https://frost.gitbook.io/iosbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://frost.gitbook.io/iosbook/flutter/life-cycles/applifecyclestate.md).

# \[Flutter] AppLifecycleState

The observable lifecycle events are:

* `inactive` — The application is in an inactive state and is not receiving user input. This event only works on iOS, as there is no equivalent event to map to on Android
* `paused` — The application is not currently visible to the user, not responding to user input, and running in the background. This is equivalent to `onPause()` in Android
* `resumed` — The application is visible and responding to user input. This is equivalent to `onPostResume()` in Android
* `suspending` — The application is suspended momentarily. This is equivalent to `onStop` in Android; it is not triggered on iOS as there is no equivalent event to map to on iOS

```
flutter: AppLifecycleState.inactive
flutter: AppLifecycleState.paused
flutter: AppLifecycleState.inactive
flutter: AppLifecycleState.resumed
```

如果我們想監聽App級別的生命週期需要使用WidgetsBinding來監聽WidgetsBindingObserver**.**

**Example:**

```
class extends StatefulWidget {

  LifeCycle({Key key}): super(key: key);

  LifeCycleState createState() => new LifeCycleState();
}

class LifeCycleState extends State<LifeCycle> with WidgetsBindingObserver {

  @override
  void initState(){
    super.initState();
    WidgetsBinding.instance.addObserver(this);
  }

  @override
  Widget build(BuildContext context){
    return new MaterialApp(
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text(''),
        ),
        body: new Center(
          child: new Text(''),
        ),
      ),
    );
  }

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

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