How to use Background Service in Xamarin -Android

Question

Good Day All

I have SignalR code that runs from the App.cs file , This obviously works when the app is opened. So now i want to move the code to the background Service. So basically in my SignalR Code i show Local Notification. i have attached a simple example . i want my SignalR code to be fired and give me a notification on the foreground when the received event received something

Example Link http://www.yowfun.com/eg/ShinyExample.zip

Thanks

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

I am not familar with SignalR. Do you want to achieve a android service that execute your SignalR code in Xamarin?

If Yes, you need to know the Background Execution Limits in Android 8.0. SO, I advice you to use Foreground service to achieve it.

And I notice you use Xamarin.Forms, if you want to start a service, create an Interface in the Xamarin.forms project:

   public interface IStartService  
   {  
       void StartForegroundServiceCompat();  
   }  

if you execute your dependence service, you can use following code.

   DependencyService.Get<IStartService>().StartForegroundServiceCompat();  

Then create a startServiceAndroid.cs in xxx.Android project to start the a service (Before android 8.0, start a service After Android 8.0 or later, you need to open a foreground service). Please see the //do you work, you can edd the new BackgroundStartup();. When the android background service is running, your BackgroundStartup could run it.

   [assembly: Dependency(typeof(startServiceAndroid))]  
   namespace ShinyExample.Droid  
   {  
       [Service]  
       class startServiceAndroid: Service, IStartService  
       {  
           public void StartForegroundServiceCompat()  
           {  
               var intent = new Intent(Android.App.Application.Context, typeof(startServiceAndroid));  
     
     
               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("Foreground")  
               .SetContentText(messageBody)  
               .SetSmallIcon(Resource.Drawable.icon1)  
               .SetOngoing(true)  
               .Build();  
               StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);  
     
     
     
               //do you work  
               new BackgroundStartup();  
     
     
                 
               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.channelName);  
               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);  
           }  
     
       }  
       
   }  

Best Regards,

Leon Lu

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