Boolean expression must not be null?

Question

Does anyone know why i got the Failed assertion: boolean expression must not be null. If I had logged in and quit the app and open the app again i should be directly in the home

Answer 1

You have a global approach error. You combine traditional and async/await methods in this code:

getLoggedInState()async{
    await HelperFunction.getUserLoggedInSharedPreference().then((value){
      setState(() {
        userIsLoggedIn = value;
      });
    });
  }

If you use async/await you should not use then method.

To implement what you want you should use something like this:

...
@override
Widget build(BuildContext context) {
  return MaterialApp(
    debugShowCheckedModeBanner: false,
    home: FutureBuilder(
      future: HelperFunction.getUserLoggedInSharedPreference(),
      builder: (context,snapshot) {
        if (snapshot.hasData) {
          // Future is ready. Take data from snapshot
          userIsLoggedIn = snapshot.data; // bool value is here
          return userIsLoggedIn ? HomeScreen() : CompanyLoadingBar();
        } else {
          // Show progress while future will be completed
          return CircularProgressIndicator();
        }
      }
    ),
  );
}
...

And also check what value is returned from HelperFunction.getUserLoggedInSharedPreference(). It seems it returns null because I think you have no already saved value. So you need to specify the default value:

final value = await SharedPreferences.getInstance().readBool(name) ?? false;