How to display local notification periodically with Flutter?

Question

I want to launch notifications periodically if a condition is checked

class notification definition

FlutterLocalNotificationsPlugin notificationsPlugin =
    FlutterLocalNotificationsPlugin();

class NotificationLocal extends StatefulWidget {
  static const routeName = '/notificaton';
  const NotificationLocal({Key? key}) : super(key: key);

  Future<void> displayNotification() async {
    notificationsPlugin.zonedSchedule(
        0,
        'Alerte Sécurité :',
        'Attention l\'aire est toxique pensez à aéré la pièce',
        tz.TZDateTime.now(tz.local).add(Duration(seconds: 5)),
        NotificationDetails(
          android: AndroidNotificationDetails(
              'channel id', 'channel name', 'channel description',
              importance: Importance.high, priority: Priority.high),
        ),
        uiLocalNotificationDateInterpretation:
            UILocalNotificationDateInterpretation.absoluteTime,
        androidAllowWhileIdle: true);
  }

  @override
  _NotificationLocalState createState() => _NotificationLocalState();
}

class _NotificationLocalState extends State<NotificationLocal> {
  @override
  void initState() {
    // TODO: implement initState

    initializeSetting();
    tz.initializeTimeZones();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
        child: ElevatedButton(
      style: ElevatedButton.styleFrom(
          primary: Colors.green,
          padding: EdgeInsets.symmetric(horizontal: 50, vertical: 20),
          textStyle: TextStyle(fontSize: 30, fontWeight: FontWeight.bold)),
      // textColor: Colors.white,
      // color: Colors.blue,
      child: Text('Login'),
      onPressed: () {
        (new NotificationLocal()).displayNotification();
      },
    ));
  }
}

void initializeSetting() async {
  var initializeAndroid = AndroidInitializationSettings('warn');
  var initializeIOS = IOSInitializationSettings();
  var initializeSetting =
      InitializationSettings(android: initializeAndroid, iOS: initializeIOS);
  await notificationsPlugin.initialize(initializeSetting);
}

when i Try to call the code below in a another class

  @override
  void initState() {
    super.initState();
    Timer.periodic(Duration(milliseconds: 10000), (timer) {
      (new NotificationLocal()).displayNotification();
    });

I got the following errors

E/flutter (20095): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: LateInitializationError: Field '_local@732310200' has not been initialized.
E/flutter (20095): #0 _local (package:timezone/src/env.dart)
E/flutter (20095): #1 local (package:timezone/src/env.dart:31:23)
E/flutter (20095): #2 NotificationLocal.displayNotification (package:weather_app/service/notification_service.dart:18:30)
E/flutter (20095): #3 _MyAppState.initState. (package:weather_app/api/api_post.dart:53:33)
E/flutter (20095): #4 _rootRunUnary (dart:async/zone.dart:1362:47)
E/flutter (20095): #5 _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter (20095): #6 _CustomZone.runUnaryGuarded (dart:async/zone.dart:1170:7)
E/flutter (20095): #7 _CustomZone.bindUnaryCallbackGuarded. (dart:async/zone.dart:1207:26)
E/flutter (20095): #8 _rootRunUnary (dart:async/zone.dart:1370:13)
E/flutter (20095): #9 _CustomZone.runUnary (dart:async/zone.dart:1265:19)
E/flutter (20095): #10 _CustomZone.bindUnaryCallback. (dart:async/zone.dart:1191:26)
E/flutter (20095): #11 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:395:19)
E/flutter (20095): #12 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:426:5)
E/flutter (20095): #13 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:184:12)
E/flutter (20095):

Answer 1

First install timezone plugin with following command:

flutter pub add timezone

After that add the following code:

import 'package:timezone/data/latest_all.dart' as tz;
import 'package:timezone/timezone.dart' as tz;

void main() async {
tz.initializeTimeZones();
runApp(const MyApp());
}

Best regards.