Pop  传参

#回调 接收参数

_navigateAndDisplaySelection(BuildContext context) async {
  final result = await Navigator.push(
    context,
    MaterialPageRoute(builder: (context) => SelectionScreen()),
  );

  // After the Selection Screen returns a result, hide any previous snackbars
  // and show the new result.
  // 等选择界面返回结果，先隐藏之前的 snackbars，结果显示在新的 snackbars 里  (After the Selection Screen returns a result, hide any previous snackbars and show the new result!)
  ScaffoldMessenger.of(context)
    ..removeCurrentSnackBar()
    ..showSnackBar(SnackBar(content: Text("$result")));
}

传参地方 Navigator.pop(context, 'Nope!');