public Guid Subscribe(Action <Notification> OnReceiveNotification, string tag) { if (_messenger.HasSubscriptionsForTag <NotificationMessage>(tag)) { return(Guid.Empty); } var subscription = _messenger.SubscribeOnMainThread <NotificationMessage>((msg) => { OnReceiveNotification(msg.Notification); }, MvxReference.Strong); _subscriptionToken.Add(subscription.Id, subscription); return(subscription.Id); }