When a route is pushed to the navigation, we may want to expect something back from it— for example, when we ask for something from the user in a new route, we can take the value returned via the pop() method's result parameter.

The push method and its variants return a Future. The Future resolves when the route is popped and the value of Future is the pop() method's result parameter.

We have seen that we can pass arguments to a new Route. As the inverse path is also possible, instead of sending a message to the second screen, we can take a message when it pops back.

In Screen 2, we just make sure to return something when doing the pop from Navigator:

// part of navigation_widgetsapp_navigation_result.dart 
class _NavigatorResultAppState
    extends State<NavigatorResultApp> {

  Widget _screen2(BuildContext context) {
    // ... hidden for brevety
    RaisedButton(
      child: Text("Back to Screen 1"),
      onPressed: () {
        Navigator.of(context).pop("Good bye from screen 2");
      },
    ),
  ...
}

The second argument in the pop method is the result from the route.

In the caller screen, we need to take the result back:

// part of navigation_widgetsapp_navigation_result.dart 
class _NavigatorResultAppState
    extends State<NavigatorResultApp> {

  Widget _screen1(BuildContext context) {
  // ... hidden for brevety

    RaisedButton(
      child: Text("Go to Screen 2"),
      onPressed: () async {
        final message = await Navigator.of(context).pushNamed('/2') ?? 
        "Came from back button";
        setState(() {
          _message = message;
        }); 
      },
    ),    
    ...
  }
}

The result of push is a Future we need to take using the await keyword. Here, we just set it to a new _message variable that is displayed in a text.