Xamarin IOS - Show local notification when application is closed

Question

I have a Xamarin IOS application that get's the users location each 10 sec, even when the app is killed. I make us of this library: "https://jamesmontemagno.github.io/GeolocatorPlugin/".

What I want is: When the app is closed or open and the user is at a specific location, I want to show a local notification. Is that even possible when the app is closed? I can't find information on this because it's always about remote notifications.

Answer 1

Notification permission should be requested as soon as the app launches by adding the following code to the FinishedLaunching method of the AppDelegate and setting the desired notification type (UNAuthorizationOptions):

...
using UserNotifications;
...



 public override bool FinishedLaunching(UIApplication application, NSDictionary launchOptions)
   {
       ....
           
        //after iOS 10
        if(UIDevice.CurrentDevice.CheckSystemVersion(10,0))
        {
            UNUserNotificationCenter center = UNUserNotificationCenter.Current;

            center.RequestAuthorization(UNAuthorizationOptions.Alert | UNAuthorizationOptions.Sound | UNAuthorizationOptions.UNAuthorizationOptions.Badge, (bool arg1, NSError arg2) =>
                 {

                 });

            center.Delegate = new NotificationDelegate();
        }

        else if(UIDevice.CurrentDevice.CheckSystemVersion(8, 0))
        {

            var settings = UIUserNotificationSettings.GetSettingsForTypes(UIUserNotificationType.Alert| UIUserNotificationType.Badge| UIUserNotificationType.Sound,new NSSet());

            UIApplication.SharedApplication.RegisterUserNotificationSettings(settings);

        }

        return true;
    }

New to iOS 10, an app can handle Notifications differently when it is in the foreground and a Notification is triggered. By providing a UNUserNotificationCenterDelegate and implementing the UserNotificationCentermethod, the app can take over responsibility for displaying the Notification. For example:

using System;
using ObjCRuntime;
using UserNotifications;


namespace workplat
{
 public class NotificationDelegate:UNUserNotificationCenterDelegate
   {
    public NotificationDelegate()
    {
    }

    public override void WillPresentNotification(UNUserNotificationCenter center, UNNotification notification, Action<UNNotificationPresentationOptions> completionHandler)
    {
        // Do something with the notification
        Console.WriteLine("Active Notification: {0}", notification);

        // Tell system to display the notification anyway or use
        // `None` to say we have handled the display locally.
        completionHandler(UNNotificationPresentationOptions.Alert|UNNotificationPresentationOptions.Sound);
    }


    public override void DidReceiveNotificationResponse(UNUserNotificationCenter center, UNNotificationResponse response, Action completionHandler)
    {
        // Take action based on Action ID
        switch (response.ActionIdentifier)
        {
            case "reply":
                // Do something
                break;
            default:
                // Take action based on identifier
                if (response.IsDefaultAction)
                {
                    // Handle default action...
                }
                else if (response.IsDismissAction)
                {
                    // Handle dismiss action
                }
                break;
        }

        // Inform caller it has been handled
        completionHandler();
    }

  }
}

To create and register a Custom Action with the system, use the following code:

 public void RegisterNotification(long time)
    {
        UNUserNotificationCenter center = UNUserNotificationCenter.Current;

        //creat a UNMutableNotificationContent which contains your notification content
        UNMutableNotificationContent notificationContent = new UNMutableNotificationContent();

        notificationContent.Title = "xxx";
        notificationContent.Body= "xxxx";

        notificationContent.Sound = UNNotificationSound.Default;

        UNTimeIntervalNotificationTrigger trigger = UNTimeIntervalNotificationTrigger.CreateTrigger(time, false);

        UNNotificationRequest request = UNNotificationRequest.FromIdentifier("FiveSecond", notificationContent, trigger);


        center.AddNotificationRequest(request,(NSError obj) => 
        {
           


        });

    }

When you call this method ,for emample:

RegisterNotification(20);//set the time you want to push notification

The notification will been pushed after 20 seconds,enen if you close your app. You could put this line after uploading the location .

I have upload my demo to my github, you can download it for your reference: Demo Link .

And you can access the link for more information and details: MicroSoft Document