Flutter + FCM: Cant change UI in onMessage method

Question

I use Firebase FCM in Flutter to inform the App when a message is received. The initState method of my widget (which returns a Scaffold) looks like this:

@override
void initState() {
super.initState();

FcmService(_fcm).saveDeviceToken();

_fcm.configure(
  onMessage: (Map<String, dynamic> message) async {
    print('Notification received');

    final snackbar = SnackBar(
      content: Text(message['notification']['title']),
      action: SnackBarAction(
        label: 'Go',
        onPressed: () => null,
      ),
    );
    Scaffold.of(context).showSnackBar(snackbar);
  },
);
}

When a message is sent to the device, the print is executed, so everything should work fine, but the SnackBar doesn't show up. I also tried showing an AlertDialog or just using setState and changing a variable displayed on a label to test whether this is a SnackBar exclusive thing, but it isn't. Nothing changed, although the method is executed.

Answer 1

You cannot get a scaffoldstate from initstate, try using a future delay method if calling it in the initstate is mandate for you or simply call it from build method.