Hide keyboard on didChangeAppLifecycleState in flutter

Question

How to hide keyboard on didChangeAppLifecycleState

I created a widget called lifecycle_widget and wrapped app with so I can listen to app lifecycle state changes

here is my lifecycle widget:

class LifeCycle extends StatefulWidget {
  final Widget child;
  const LifeCycle({required this.child});
  @override
  _LifeCycleState createState() => _LifeCycleState();
}
class _LifeCycleState extends State<LifeCycle> with WidgetsBindingObserver {
  @override
  Widget build(BuildContext context) {
    return GestureDetector(child: widget.child,
    onTap: () {

        FocusScopeNode currentFocus = FocusScope.of(context);
        if (!currentFocus.hasPrimaryFocus && currentFocus.focusedChild != null) {
          currentFocus.focusedChild!.unfocus();
        }

        SystemChannels.textInput.invokeMethod('TextInput.hide');
      },
    );
  }


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


  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    print('state = $state');
    FocusScopeNode currentFocus = FocusScope.of(context);
    if (!currentFocus.hasPrimaryFocus && currentFocus.focusedChild != null) {
      currentFocus.focusedChild!.unfocus();
    }
    SystemChannels.textInput.invokeMethod('TextInput.hide');

  }
}

and here how I wrapped my app:

@override
Widget build(BuildContext context) {
  var localizationDelegate = LocalizedApp.of(context).delegate;
  return LifeCycle(child: LocalizationProvider(
      state: LocalizationProvider.of(context).state,
      child: DismissKeyboard(child: GetMaterialApp(
          title: 'FastFill',
          onGenerateRoute: AppRouter.generateRoute,
          debugShowCheckedModeBanner: false,
          localizationsDelegates: [
            localizationDelegate,
            GlobalMaterialLocalizations.delegate,
            GlobalWidgetsLocalizations.delegate,
            GlobalCupertinoLocalizations.delegate,
            DefaultWidgetsLocalizations.delegate,
          ],
          supportedLocales: localizationDelegate.supportedLocales,
          locale: _locale,
          theme: ThemeData(
              primaryColor: primaryColor1,
              accentColor: primaryColor2,
              fontFamily: isArabic() ? 'Poppins' : 'Poppins'),
          initialRoute: (isSigned) ? HomePage.route : LanguagePage.route,
      ))));
}

But it does not work and does not do the job ! when app goes into background and then back to it the keyboard stays and does not response!