<code>class _MyHomePageState extends State&lt;MyHomePage&gt; with WidgetsBindingObserver {
  AppLifecycleState? _notification; 
  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    setState(() {
      _notification = state;
    });
  }

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

  @override
  void dispose() {
    WidgetsBinding.instance?.removeObserver(this);
    super.dispose();
  }
}
</code>