web services - How to running method webservice in background from android xamarin form

Question

I want running this method UpdateStatus when he close app

It is my coding method UpdateStatus in android:

String id = "";

var id = Application.Current.Properties["Id"].ToString();

User user = new User(id);
user.Id = id;
user.Datetime = time;

var responseStatus = await api.UpdateStatus(new UpdateStatusQuery(user));

Could you help me ?

Answer 1

In the Android, When you close your applcation, based on my research, above code can not be run, because all of threads or services will be killed when applcation is killed.

If you want to run above code when application in the background, you can can use background service to achieve that, due to background execution limits in Android 8.0 or later, if you code need some time to execute, and you want code running stably, Foreground Services is a good choice.

In xamarin forms, you can use dependenceService in the OnSleep method of App.xaml.cs

OnSleep - called each time the application goes to the background.

You can create a interface.

IService.cs

public interface IService
{
    void Start();
}

Then achieved DependentService to start a Foreground Service.

[assembly: Xamarin.Forms.Dependency(typeof(DependentService))]
namespace TabGuesture.Droid
{
[Service]
public class DependentService : Service, IService
{
    public void Start()
    {
        var intent = new Intent(Android.App.Application.Context, 
 typeof(DependentService));


        if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
        {
            Android.App.Application.Context.StartForegroundService(intent);
        }
        else
        {
            Android.App.Application.Context.StartService(intent);
        }
    }

    public override IBinder OnBind(Intent intent)
    {
        return null;
    }
    public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;
    public override StartCommandResult OnStartCommand(Intent intent, 
    StartCommandFlags flags, int startId)
    {
        // From shared code or in your PCL

        CreateNotificationChannel();
        string messageBody = "service starting";

        var notification = new Notification.Builder(this, "10111")
        .SetContentTitle(Resources.GetString(Resource.String.app_name))
        .SetContentText(messageBody)
        .SetSmallIcon(Resource.Drawable.main)
        .SetOngoing(true)
        .Build();
        StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
        //==============================do you work=====================

        String id = "";

        var id = Application.Current.Properties["Id"].ToString();
        User user = new User(id);
        user.Id = id;
        user.Datetime = time;
        var responseStatus = await api.UpdateStatus(new UpdateStatusQuery(user));

        return StartCommandResult.Sticky;
    }


    void CreateNotificationChannel()
    {
        if (Build.VERSION.SdkInt < BuildVersionCodes.O)
        {
            // Notification channels are new in API 26 (and not a part of the
            // support library). There is no need to create a notification
            // channel on older versions of Android.
            return;
        }

        var channelName = Resources.GetString(Resource.String.channel_name);
        var channelDescription = GetString(Resource.String.channel_description);
        var channel = new NotificationChannel("10111", channelName, NotificationImportance.Default)
        {
            Description = channelDescription
        };

        var notificationManager = (NotificationManager)GetSystemService(NotificationService);
        notificationManager.CreateNotificationChannel(channel);
    }
}
}

Here is similar thread: How to create service doing work at period time in Xamarin.Forms?