Local Push notification not working in Xamarin iOS

问题

I am using Xamarin.forms and implemented Local push notification for iOS. It is working successfully when I am debugging the app through visual studio even when the app is minimized, the app can able to receive the notification. But while running the app directly without debugging through visual studio, the app is not able to display the notification. Kindly guide me on this.

Then I also tried by releasing the app to the app store but experienced the same, the app is not able to receive the notification it not even in foreground mode.

I already have selected the "Background fetch" property under Background Modes in Info.plist. I have also added below the line in my FinishedLaunching method

UIApplication.SharedApplication.SetMinimumBackgroundFetchInterval(UIApplication.BackgroundFetchIntervalMinimum);

Entire Implementation of code is as below

   public override bool FinishedLaunching(UIApplication app, NSDictionary options)
    {
        try
        {
            UIApplication.SharedApplication.SetMinimumBackgroundFetchInterval(UIApplication.BackgroundFetchIntervalMinimum);

            try
            {                    

                if (UIDevice.CurrentDevice.CheckSystemVersion(10, 0))
                {
                    UNUserNotificationCenter.Current.RequestAuthorization(UNAuthorizationOptions.Alert |
                        UNAuthorizationOptions.Sound |
                        UNAuthorizationOptions.Sound,
                        (granted, error) =>
                        {
                            if (granted)
                            {
                                InvokeOnMainThread(UIApplication.SharedApplication.RegisterForRemoteNotifications);                                    
                            }
                        });
                }
                else if (UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
                {
                    var pushSettings = UIUserNotificationSettings.GetSettingsForTypes(
                    UIUserNotificationType.Alert | UIUserNotificationType.Badge | UIUserNotificationType.Sound,
                    new NSSet());

                    UIApplication.SharedApplication.RegisterUserNotificationSettings(pushSettings);
                    UIApplication.SharedApplication.RegisterForRemoteNotifications();
                }
                else
                {
                    UIRemoteNotificationType notificationTypes = UIRemoteNotificationType.Alert | UIRemoteNotificationType.Badge | UIRemoteNotificationType.Sound;
                    UIApplication.SharedApplication.RegisterForRemoteNotificationTypes(notificationTypes);
                }

                bool IsRegistered = UIApplication.SharedApplication.IsRegisteredForRemoteNotifications;
            }
            catch (Exception ex)
            {
                UIAlertView avAlert = new UIAlertView("FinishedLaunching Push Notification Exception", ex.Message, null, "OK", null);
                avAlert.Show();
            }

            UNUserNotificationCenter.Current.Delegate = new UserNotificationCenterDelegate();

            LoadApplication(new MessengerClient.App());

        }
        catch (Exception ex)
        {
            NativeHelper.SendUnhandledException(ex, NativeHelper.iOS + ": FinishedLaunching");
        }
        return base.FinishedLaunching(app, options);
    }

    public override void ReceivedLocalNotification(UIApplication application, UILocalNotification notification)
    {  
        /// reset our badge
        UIApplication.SharedApplication.ApplicationIconBadgeNumber = 0;

        /// Cancel/clear all Local notifications fronm the tray.
        UIApplication.SharedApplication.CancelLocalNotification(notification);

        /// Cancel/clear all notifications fronm the tray.
        UIApplication.SharedApplication.CancelAllLocalNotifications();
    }

code for displaying the notification is as below.

UILocalNotification notification = new UILocalNotification();
        notification.FireDate = NSDate.FromTimeIntervalSinceNow(1);
        notification.AlertAction = title;
        notification.AlertBody = content;
        notification.AlertTitle = title;
        notification.SoundName = UILocalNotification.DefaultSoundName;
        notification.ApplicationIconBadgeNumber = 1;            
        UIApplication.SharedApplication.ScheduleLocalNotification(notification);

I know this is the repeat question but, I tried all the workaround but didn't work for me.

回答1:

You can have a check with this Notifications in Xamarin.iOS .

iOS applications handle remote and local notifications in almost exactly the same fashion. When an application is running, the ReceivedLocalNotification method or the ReceivedRemoteNotification method on the AppDelegate class will be called, and the notification information will be passed as a parameter.

An application can handle a notification in different ways. For instance, the application might just display an alert to remind users about some event. Or the notification might be used to display an alert to the user that a process has finished, such as synching files to a server.

The following code shows how to handle a local notification and display an alert and reset the badge number to zero:

public override void ReceivedLocalNotification(UIApplication application, UILocalNotification notification)
{
    // show an alert
    UIAlertController okayAlertController = UIAlertController.Create(notification.AlertAction, notification.AlertBody, UIAlertControllerStyle.Alert);
    okayAlertController.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));

    Window.RootViewController.PresentViewController(okayAlertController, true, null);

    // reset our badge
    UIApplication.SharedApplication.ApplicationIconBadgeNumber = 0;
}

In addition , there is a sample you can download to check . It works no matter in Debug or Release Model in my local site (iOS 13.3).

The effect :

回答2:

Just add this code in your AppDelegate DidFinishLaunching and notification will start working in the background. BackgroundTask- showNotification may get canceled sometime, for me whenever my dashboard is loaded, I guess as it has multiple API Calls. so add it in your DidEnterBackground Delegate as well with different taskID, to start a new background task. It works fine for me.

nint taskID = yourTaskID;
taskID = application.BeginBackgroundTask("showNotification", expirationHandler: ()=> {
     UIApplication.SharedApplication.EndBackgroundTask(taskID);
});

来源：https://stackoverflow.com/questions/60755808/local-push-notification-not-working-in-xamarin-ios