Local Notifications with flutter local notifications in Flutter

dependencies:
  flutter_local_notifications

import 'package:flutter_local_notifications/flutter_local_notifications.dart';

final flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();

  const androidSettings = AndroidInitializationSettings('@mipmap/ic_launcher');
  final iosSettings = DarwinInitializationSettings(
    requestAlertPermission: true,
    requestBadgePermission: true,
    requestSoundPermission: true,
  );
  final initSettings = InitializationSettings(android: androidSettings, iOS: iosSettings);

  await flutterLocalNotificationsPlugin.initialize(
    initSettings,
    onDidReceiveNotificationResponse: (response) {
      // Handle tap (payload in response.payload)
    },
  );

  runApp(MyApp());
}

Future<void> showImmediateNotification() async {
  const androidDetails = AndroidNotificationDetails(
    'default_channel', 'Default', channelDescription: 'General notifications',
    importance: Importance.max, priority: Priority.high,
  );
  const iosDetails = DarwinNotificationDetails();
  const notificationDetails = NotificationDetails(android: androidDetails, iOS: iosDetails);

  await flutterLocalNotificationsPlugin.show(
    0, 'Hello!', 'This is an immediate notification.', notificationDetails,
    payload: 'immediate_payload',
  );
}

Future<void> scheduleNotification() async {
  final scheduledTime = DateTime.now().add(Duration(hours: 2));
  await flutterLocalNotificationsPlugin.zonedSchedule(
    1,
    'Reminder',
    'Don’t forget to check your tasks.',
    tz.TZDateTime.from(scheduledTime, tz.local),
    const NotificationDetails(
      android: AndroidNotificationDetails('reminder_channel', 'Reminders'),
      iOS: DarwinNotificationDetails(),
    ),
    androidAllowWhileIdle: true,
    uiLocalNotificationDateInterpretation: UILocalNotificationDateInterpretation.absoluteTime,
    payload: 'scheduled_payload',
  );
}

final androidDetails = AndroidNotificationDetails(
  'custom_channel', 'Custom',
  icon: 'app_icon',
  largeIcon: const DrawableResourceAndroidBitmap('large_icon'),
  sound: RawResourceAndroidNotificationSound('notification_sound'),
  importance: Importance.high, priority: Priority.high,
);

onDidReceiveNotificationResponse: (response) {
  final payload = response.payload;
  if (payload == 'scheduled_payload') {
    navigatorKey.currentState?.pushNamed('/tasks');
  }
}

await flutterLocalNotificationsPlugin.periodicallyShow(
  2,
  'Stand Up',
  'Time to stretch your legs.',
  RepeatInterval.hourly,
  notificationDetails,
  androidAllowWhileIdle: true,
);

tz.TZDateTime nextInstance(int hour, int minute, Day day) {
  final now = tz.TZDateTime.now(tz.local);
  var scheduled = tz.TZDateTime(tz.local, now.year, now.month, now.day, hour, minute);
  while (scheduled.weekday != day) {
    scheduled = scheduled.add(Duration(days: 1));
  }
  if (scheduled.isBefore(now)) scheduled = scheduled.add(Duration(days: 7));
  return scheduled;
}