flutter snackbar
final snackBar = SnackBar(
content: Text('Yay! A SnackBar!'),
action: SnackBarAction(
label: 'Undo',
onPressed: () {
// Some code to undo the change.
},
),
);
// Find the Scaffold in the widget tree and use
// it to show a SnackBar.
Scaffold.of(context).showSnackBar(snackBar);