Вы инициализировали FlutterLocalNotificationsPlugin ? Если нет, попробуйте добавить приведенные ниже операторы в initState () , как показано ниже
@override
void initState() {
super.initState();
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin = new
FlutterLocalNotificationsPlugin();
// initialise the plugin. app_icon needs to be a added as a drawable resource to the Android head project
var initializationSettingsAndroid =
new AndroidInitializationSettings('ic_launcher');
var initializationSettingsIOS = IOSInitializationSettings(
onDidReceiveLocalNotification: onDidReceiveLocalNotification);
var initializationSettings = InitializationSettings(
initializationSettingsAndroid, initializationSettingsIOS);
flutterLocalNotificationsPlugin.initialize(initializationSettings,
onSelectNotification: onSelectNotification);
}
, попробуйте это и дайте мне знать