[Flutter] AppLifeCycleState.detached is not called When App is closed

Future<void> onAppClose({required String userId}) async {
await FirebaseFirestore.instance
.collection(FirebaseConstants.usersCollection)
.doc(userId)
.update({'isOnline': false});
}

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

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

@override
void didChangeAppLifecycleState(AppLifecycleState state) {
final userId = ref.read(currentDeliveryUserProvider)?.reference.id;
print("state--------------------$state");
if (userId != null) {
if (state == AppLifecycleState.detached) {
// The app is completely closing
onAppClose(userId: userId);
}
}
}

@override
Widget build(BuildContext context) {
h = MediaQuery.of(context).size.height;
w = MediaQuery.of(context).size.width;
return GestureDetector(
onTap: () {
FocusManager.instance.primaryFocus?.unfocus();
},
child: MaterialApp(
title: 'ONtrend Partners',
home: const SplashScreen(),
// home: TestFile(),
theme: ThemeData(
textTheme: GoogleFonts.dmSansTextTheme(),
),
debugShowCheckedModeBanner: false,
),
);
}
}


I'm building a delivery app in Flutter, and I'm trying to set the user's isOnline status to false in Firebase when the app is closed. I've been using WidgetsBindingObserver to listen for AppLifecycleState changes, and everything works fine for AppLifeCycleState.paused and AppLifeCycleState.inactive. However, I noticed that AppLifeCycleState.detached is not being triggered when the app is completely closed (terminated).

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