xamarin.android Receiver on BOOT_COMPLETED error

Question

I am trying to make a simple service which starts with device boot. Thing is that device return message "Unfortunately, [app_name] has stopped."

I am struggling with this problem from few hours, with looking for mistake, but it is too simple.. Hope, you guys can help me with this problem.

This is my code:

AndroidManifest.xml

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

<application android:allowBackup="true" android:label="@string/app_name">


    <receiver android:name=".StartReceiver">
          <intent-filter>
              <action android:name="android.intent.action.BOOT_COMPLETED"/>
          </intent-filter>
    </receiver>

  <service android:name=".PService" />
</application>

StartReceiver.cs

[BroadcastReceiver]
[IntentFilter(new[] { Intent.ActionBootCompleted })]
public class StartReceiver : BroadcastReceiver
{
    public override void OnReceive(Context context, Intent intent)
    {
        Intent startIntent = new Intent(context, typeof(PService));
        context.StartService(startIntent);
    }
}

and lastly PService.cs

[Service]
    public class PService : Service
    {
        public override void OnCreate()
        {
            base.OnCreate();
        }

        public override IBinder OnBind(Intent intent)
        {
            return null;
        }


        public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {
            Toast.MakeText(this, "Start", ToastLength.Short).Show();
            return StartCommandResult.Sticky;
        }

        public override void OnDestroy()
        {
            base.OnDestroy(); 

            Toast.MakeText(this, "Stop", ToastLength.Short).Show();
        }
    }

Additional this service application is targetted to API 19 (4.4.2 KitKat) Android version.

I think there will be really small mistake, made by me but truly I cant find it out.. Thanks in advance for any help.

Answer 1

By adding the receiver in the manifest and via the BroadcastReceiverAttribute you have two receivers in your manifest. Plus the one in your manifest will not work since it is not the MD5-based Java name that Xamarin creates by default.

Via Attributes

1) Remove the receiver and boot permission from your manifest

2) Add your boot permissions via an attribute)

[assembly: UsesPermission(Manifest.Permission.ReceiveBootCompleted)]

3) Add the manifest entry via attributes:

[BroadcastReceiver(Enabled = true)]
[IntentFilter(new[] { Intent.ActionBootCompleted })]    
public class BootBroadcastReceiver : BroadcastReceiver

Via manifest

1) Add the manifest entry for the boot permission

<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

2) Add the receiver and use a full qualify Java class name:

<receiver android:name="com.yourpackagename.app.BootBroadcastReceiver">
      <intent-filter>
          <action android:name="android.intent.action.BOOT_COMPLETED"/>
      </intent-filter>
</receiver>

3) Add a Name parameter to the BroadcastReceiverAttribute for the fully qualified Java class name that you used in the manifest

[BroadcastReceiver(Name = "com.yourpackagename.app.BootBroadcastReceiver", Enabled = true)]
[IntentFilter(new[] { Intent.ActionBootCompleted })]    
public class BootBroadcastReceiver : BroadcastReceiver

Answer 2

There are a few gotchas I faced when working on this:

1. Android ignores broadcast receivers of applications that have never been started by the user. When deploying using Visual Studio, your app is installed fresh and started automatically which doesn't satisfy the "user-started" condition so your Broadcast Receiver won't get the ACTION_BOOT_COMPLETED intent. You will need to close the app after deployment (I remove it from my Recent Apps list) and manually re-open it again before it begins to receive implicit intent. This tripped me up tremendously and I had spent several hours till I came across someone else who discovered this.

2. If you're using Xamarin Forms, make sure you're not using DependencyService.Get() in your Broadcast Receiver as that requires Xamarin Forms to be initialized but the Android system doesn't call your MainActivity when triggering your BroadcastReceiver. The result is that the BroadcastReceiver does in fact get started but because it throws an Exception, you might not realize that it got called at all. I suggest using the Android implementation of the DI service directly in these cases.

Other than that, my BroadcastReceiver was pretty standard:

[BroadcastReceiver(Enabled = true, Exported = true, DirectBootAware = true)]
[IntentFilter(new[] { Intent.ActionLockedBootCompleted })]
public class RebootReceiver : BroadcastReceiver

I receive the ACTION_LOCKED_BOOT_COMPLETED intent which is broadcast earlier than the ACTION_BOOT_COMPLETED but requires the DirectBootAware property to be enabled and has some more specific limits regarding its usage. According to your needs, Intent.ActionBootCompleted without the DirectBootAware property could be just as sufficient.

And my Assembly.info file included this:

[assembly: UsesPermission(Android.Manifest.Permission.ReceiveBootCompleted)]

Answer 3

2022 ANSWER

After almost 3 hours banging my head on the wall, I finally got it to work. All answers are out dated since Google made a few API changes. Anyway, here is what worked for me.

How I tested

1. Launch App on phone (Just to clear out any confusions, I even launched it using my debugger to confirm it was not due to 'debug' mode). Fyi, I am using Xiaomi Pocophone F1. My App is targeting API level 30.
2. Make the App schedule notifications to appear 3 minutes later
3. Reboot the phone
4. Wait for 3 minutes (Note that I am NOT launching my App. I also do not have App autostart permission enabled for me. There was some old answer suggesting autostart must be on. This is WRONG i.e. not required)
5. After 3 minutes the notification appears! This means during reboot the Boot BroadcastReceiver fired up.

The code

[assembly: UsesPermission (Manifest.Permission.ReceiveBootCompleted)]
namespace MyApp.Droid
{
    [BroadcastReceiver(Name = "com.myapp.whatever.BootReceiver", Enabled = true)]
    [IntentFilter(new[] { Intent.ActionBootCompleted })]    
    public class BootReceiver : BroadcastReceiver
    {
        public override void OnReceive(Context context, Intent intent)
        {
            RescheduleNotifications();
        }

        public void RescheduleNotifications()
        {
            try
            {
                AppCenter.Start("android=cfc33334-8f5e-4ab3-1232-e8712345c860;"
                    //"ios={Your iOS App secret here}",
                    , typeof(Crashes));
                
                //Make sure all services are instantiated
                AppCore.DeviceService = new DeviceService();
                AppCore.FbService = new FBService();
                AppCore.AppService = new AppService();
                AppCore.DeviceService.ScheduleNotifications(notif.Notifications, false);
            }
            catch (Exception e)
            {
                Crashes.TrackError(e);
            }
        
        }
    }
}

Notes on my code

• I am using MS App Center to track crashes. You may omit these parts.
• Remember that the OnReceive is fired alone (without Main Activity being fired). So make sure your code can run and does not throw any exceptions.
• In "com.myapp.whatever.BootReceiver" replace "com.myapp.whatever" with your app's package name

The android manifest

<uses-sdk android:minSdkVersion="21" android:targetSdkVersion="30" />
<application ....>
<receiver android:enabled="true" android:name="com.myapp.whatever.BootReceiver" android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
                <action android:name="android.intent.action.QUICKBOOT_POWERON" />
            </intent-filter>
        </receiver>
    </application>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>