How to do it...

We're going to take a small break from the stopwatch for this recipe: 

1. Create a new file called login_screen.dart and generate the code snippet for a new StatefulWidget by typing stful and tapping Enter. Your IDE will automatically create a placeholder widget and its state class. 

2. Name this class LoginScreen. The State class will automatically be named _LoginScreenState. Don't forget to fix your missing imports by bringing in the material library.

3. Our login screen needs to know whether the user is logged in to show the appropriate widget tree. We can handle this by having a boolean property called loggedIn and forking the widget tree accordingly.

4. Add the following code just under the class declaration of _LoginScreenState:

bool loggedIn = false;
String name;

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text('Login'),
    ),
   ...