flutter navigator code example

Example 1: flutter push route

// Within the `FirstRoute` widget
onPressed: () {
  Navigator.push(
    context,
    MaterialPageRoute(builder: (context) => SecondRoute()),
  );
}

Example 2: flutter not navigating to a new screen

Wrap the new screen with a Scaffold widget

//navigation page
return GestureDetector(
  onTap: () {
    Navigator.push(
    context,
    MaterialPageRoute(
    	builder: (context) => DestinationScreen()),
  );
}

// new screen page
class _DestinationScreenState extends State<DestinationScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold();
  }
}

Example 3: flutter unload screen from stack

Navigator.pushAndRemoveUntil(
  context,
  MaterialPageRoute(builder: (context) => MainPage()),
  (Route<dynamic> route) => false,
);

Example 4: flutter push and pop doesnt work

PROBLEM: flutter push and pop doesnt work

SOLUTION:
You are using MaterialApp more then one time in your project, you should only have one instance of MaterialApp 
as it holds your root configuration.

Ctrl + Shift+ F type MaterialApp Search and try to remove MatrialApp with Scaffold
you need to provide only one MaterialApp. And it shoud work...