flutter_server_box/lib/core/utils/misc.dart

import 'package:fl_lib/fl_lib.dart';
import 'package:plain_notification_token/plain_notification_token.dart';

Future<String?> getToken() async {
  if (isIOS) {
    final plainNotificationToken = PlainNotificationToken();
    plainNotificationToken.requestPermission();

    // If you want to wait until Permission dialog close,
    // you need wait changing setting registered.
    await plainNotificationToken.onIosSettingsRegistered.first;
    return await plainNotificationToken.getToken();
  }
  return null;
}