AppLifcycleState.didChangeLifecycleState( )function is not called when app comes foreground or in background - dart

Question

when i open my app or runs in the background the didChangeAppLifecycleState() is not called and the print statements are not executed.
import 'package:flutter/widgets.dart';
import 'package:flutter/material.dart';
void main(){
runApp(
MaterialApp(
home: Home(),
)
);
}
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> with WidgetsBindingObserver{
AppLifecycleState state;
#override
void initState() {
super.initState();
WidgetsBinding.instance.addObserver(this);
}
#override
void dispose() {
WidgetsBinding.instance.removeObserver(this);
super.dispose();
}
void didChangeAppLifeCycleState(AppLifecycleState appLifecycleState) {
state = appLifecycleState;
print(appLifecycleState);
print(":::::::");
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Container(
child: Center(
child:Text("hi")
),
),
);
}
}
}
the print statements in the didChangeAppLifeCycleState() is not executing.

Answer 1

This isn't the answer to the OP's problem, every time that I have had this problem I have just forgotten to call WidgetsBinding.instance.addObserver(this); in initState().
If didChangeAppLifecycleState isn't called for you, don't forget to add your implementing class as a listener.
See the OP's code in initState() and dispose() and make sure you do the same.

Answer 2

There was a typo (lowercase "c" in "Lifecycle"), it should be didChangeAppLifecycleState:
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
state = state;
print(state);
print(":::::::");
}
Update: Don't forget to add observer in initState() and remove observer in dispose()
#override
void initState() {
super.initState();
WidgetsBinding.instance!.addObserver(this);
}
// ...
#override
void dispose() {
WidgetsBinding.instance!.removeObserver(this);
super.dispose();
}
Hope it helps!

Answer 3

I had to combine codes from the question and the above 2 answers to get the final result. So let me add a simple sample that illustrates how to use AppLifeCycleState properly.
void main() {
runApp(MyApp());
}
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 dispose() {
WidgetsBinding.instance.removeObserver(this);
super.dispose();
}
#override
void didChangeAppLifecycleState(AppLifecycleState state) {
switch (state) {
case AppLifecycleState.resumed:
// --
print('Resumed');
break;
case AppLifecycleState.inactive:
// --
print('Inactive');
break;
case AppLifecycleState.paused:
// --
print('Paused');
break;
case AppLifecycleState.detached:
// --
print('Detached');
break;
}
}
#override
Widget build(BuildContext context) {
return Container();
}
}