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foreground service never stop xamarin android

i have xamarin android application that read from clipboard and write to it. it uses foreground services if the user hit the button. the problem is when the user hit the button again the services disappear from running services but still doing it's job (editing copied text). how can i completely stop it from working?
foreground.cs:
public override IBinder OnBind(Intent intent)
{
return null;
}
public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
{
Clipboard.ClipboardContentChanged += async (o, e) =>
{
var text = await Clipboard.GetTextAsync();
Toast.MakeText(this, text, ToastLength.Long).Show();
if (text.Contains("#"))
{
await Clipboard.SetTextAsync(text.Replace("#", ""));
}
};
Notification notif = ReturnNotif();
StartForeground(1, notif);
return StartCommandResult.NotSticky;
}
public override void OnDestroy()
{
base.OnDestroy();
}
public override void OnCreate()
{
base.OnCreate();
}
public override bool StopService(Intent name)
{
StopForeground(true);
StopSelf();
return base.StopService(name);
}
MainActivity.cs:
if (id == Resource.Id.myService)
{
if (count != 1)
{
count = 1;
var intent = new Intent(this, typeof(foreground));
intent.SetAction("No");
if (Build.VERSION.SdkInt >= BuildVersionCodes.O)
{
StartForegroundService(intent);
}
else
{
StartService(intent);
}
}
else
{
var intent = new Intent(this,typeof(foreground));
StopService(intent);
Toast.MakeText(this, "Service Stopped", ToastLength.Long).Show();
count = 0;
}
}
what i am doing wrong ?
Edit :
Service will completely stops if the app is removed from recently used apps.

In your MyForegroundService.cs. Just add StopForeground(true) in OnDestroy() method like following code.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
namespace ForegroundServiceDemo
{
[Service]
class MyForegroundService : Service
{
public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
CreateNotificationChannel();
string messageBody = "service starting";
// / Create an Intent for the activity you want to start
Intent resultIntent = new Intent(this,typeof(Activity1));
// Create the TaskStackBuilder and add the intent, which inflates the back stack
TaskStackBuilder stackBuilder = TaskStackBuilder.Create(this);
stackBuilder.AddNextIntentWithParentStack(resultIntent);
// Get the PendingIntent containing the entire back stack
PendingIntent resultPendingIntent = stackBuilder.GetPendingIntent(0, PendingIntentFlags.UpdateCurrent);
var notification = new Notification.Builder(this, "10111")
.SetContentIntent(resultPendingIntent)
.SetContentTitle("Foreground")
.SetContentText(messageBody)
.SetSmallIcon(Resource.Drawable.main)
.SetOngoing(true)
.Build();
StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
//do you work
return StartCommandResult.Sticky;
}
public override void OnDestroy()
{
base.OnDestroy();
StopForeground(true);
}
public override IBinder OnBind(Intent intent)
{
return null;
}
void CreateNotificationChannel()
{
if (Build.VERSION.SdkInt < BuildVersionCodes.O)
{
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);
}
}
}
When you want to stop it. Just call following code.
Android.App.Application.Context.StopService(intent);
Here is my code in the Activity.
public class MainActivity : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.activity_main);
Button button1 = FindViewById<Button>(Resource.Id.button1);
Button button2 = FindViewById<Button>(Resource.Id.button2);
button2.Click += Button2_Click;
button1.Click += Button1_Click;
}
Intent intent;
private void Button2_Click(object sender, System.EventArgs e)
{
// stop foreground service.
Android.App.Application.Context.StopService(intent);
}
private void Button1_Click(object sender, System.EventArgs e)
{
intent = new Intent(Android.App.Application.Context, typeof(MyForegroundService));
// start foreground service.
if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
{
StartForegroundService(intent);
}
}
Here is running GIF.
====Update====
the expected behavior is : when service stopped user can copy and paste normally without the service interference
You can use following way to achieve that.Use Clipboard.ClipboardContentChanged += Clipboard_ClipboardContentChanged; to execute the behavior, use Clipboard.ClipboardContentChanged -= Clipboard_ClipboardContentChanged; to disable the behavior in the OnDistory method.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Xamarin.Essentials;
namespace ForegroundServiceDemo
{
[Service]
class MyForegroundService : Service
{
public const int SERVICE_RUNNING_NOTIFICATION_ID = 10000;
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
CreateNotificationChannel();
string messageBody = "service starting";
Clipboard.ClipboardContentChanged += Clipboard_ClipboardContentChanged;
// / Create an Intent for the activity you want to start
Intent resultIntent = new Intent(this,typeof(Activity1));
// Create the TaskStackBuilder and add the intent, which inflates the back stack
TaskStackBuilder stackBuilder = TaskStackBuilder.Create(this);
stackBuilder.AddNextIntentWithParentStack(resultIntent);
// Get the PendingIntent containing the entire back stack
PendingIntent resultPendingIntent = stackBuilder.GetPendingIntent(0, PendingIntentFlags.UpdateCurrent);
var notification = new Notification.Builder(this, "10111")
.SetContentIntent(resultPendingIntent)
.SetContentTitle("Foreground")
.SetContentText(messageBody)
.SetSmallIcon(Resource.Drawable.main)
.SetOngoing(true)
.Build();
StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
//do you work
return StartCommandResult.Sticky;
}
private async void Clipboard_ClipboardContentChanged(object sender, EventArgs e)
{
//throw new NotImplementedException();
var text = await Clipboard.GetTextAsync();
Toast.MakeText(this, text, ToastLength.Long).Show();
if (text.Contains("#"))
{
await Clipboard.SetTextAsync(text.Replace("#", ""));
}
}
public override void OnDestroy()
{
base.OnDestroy();
Clipboard.ClipboardContentChanged -= Clipboard_ClipboardContentChanged;
StopForeground(true);
}
public override IBinder OnBind(Intent intent)
{
return null;
}
void CreateNotificationChannel()
{
if (Build.VERSION.SdkInt < BuildVersionCodes.O)
{
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 run GIF.

To prevent this issues, add a "myServiceIsRunning" bool value in the Properties dictionary when you start your foreground method like this:
Application.Current.Properties["myServiceIsRunning"] = true
With a get function or whatever you want, before start the foreground method, verify if the key "myServiceIsRunning" exist, and if it exist, how is his status:
public bool getRunningStateMyService(){
bool myServiceIsRunningValue;
if (Application.Current.Properties.ContainsKey("myServiceIsRunning"))
{
myServiceIsRunningValue = Convert.ToBoolean(Application.Current.Properties["myServiceIsRunning"]);
}
else
{
myServiceIsRunningValue = false;
}
return locationServiceIsRunning;
}
After you get the value, with a simple if{}/else{}, you can choose to start a new instance or not if you're service is running or not. Or, in you're case just prevent the foreground method continue to run.
Don't forget to set your value to false when you destroy the foreground method.
the Properties dictionary can store data trought closing app to. you can have more infos here:
https://learn.microsoft.com/fr-fr/xamarin/xamarin-forms/app-fundamentals/application-class#Properties_Dictionary

java.lang.IllegalArgumentException: No such service ComponentInfo{/com.SampleApp.AttendanceApp.ServiceClass}

I am using Xamarin Android to build an app which should allow the app to keep sending a driver's location every 15 minutes so that I can keep track of his movement. I used JobScheduler to get this done. My project is very simple now and only contains the following 3 files:
MainActivity.cs
AttendancePage.cs (Content page, interact with UI button to start the service)
ServiceClass.cs
Methods in Main Activity.cs
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
scheduler = (JobScheduler)GetSystemService(JobSchedulerService);
LoadApplication(new App()); //This line will then jump to AttendancePage.cs
}
public void ScheduleJob()
{
ComponentName componentName = new ComponentName(this, Java.Lang.Class.FromType(typeof(ServiceClass)));
JobInfo info = new JobInfo.Builder(123, componentName)
.SetPersisted(true)
.SetPeriodic(60000)
.Build();
int resultCode = scheduler.Schedule(info); //The error show when hit this line.
if (resultCode == JobScheduler.ResultSuccess)
{
Log.Info("Message", "Job Schedule!");
}
else
{
Log.Info("Message", "Job shceduling failed");
}
}
public void CancelJob()
{
scheduler.Cancel(123);
}
AttendancePage.cs
public partial class AttendancePage : ContentPage
{
MainActivity main = new MainActivity();
public AttendancePage()
{
InitializeComponent();
Title = "Attendance App";
}
//Button OnClickEvent
async void ScheduleJob(object s, EventArgs e)
{
main.ScheduleJob();
}
//Button OnClickEvent
async void CancelJob(object s, EventArgs e)
{
main.CancelJob();
}
}
ServiceClass.cs
[Service(Name = "com.SampleApp.AttendanceApp.ServiceClass", Permission = "android.permission.BIND_JOB_SERVICE")]
public class ServiceClass : JobService
{
public ServiceClass()
{
}
public override bool OnStartJob(JobParameters jobParamsOnStart)
{
doBackgroundWork(jobParamsOnStart);
return true;
}
private void doBackgroundWork(JobParameters jobParam)
{
//My code to send driver's location
TestingPage.GetGPS();
JobFinished(jobParam, false);
}
public override bool OnStopJob(JobParameters jobParamsOnStop)
{
return false;
}
}
I have added the service tag inside AndroidManifest.xml as well.
<service android:name=".ServiceClass"
android:permission="android.permission.BIND_JOB_SERVICE"
android:exported="true" />
I have no idea why the error is still there. The error is from the line scheduler.Schedule(JobInfo). Anyone has another possible solution? I am frustrated on solving this. Will the reason be I can't debug on the service but only can straight away run in release mode? Please help.

Froms shared code it works in Xamarin.Android project , however here is a Xamarin.Forms project . It can not work.
In AttendancePage.cs , you create a new MainActivity to invoke the native method ScheduleJob and CancelJob . This will not find the JobScheduler in native ,then it will return null .
No such service ComponentInfo{/com.SampleApp.AttendanceApp.ServiceClass}
If you want to invoke native method , you can have a try with DependencyService in Xamarin Forms .
At least need to create a Interface in Forms to invoke :
public interface IJobSchedulerService
{
//Start JobSchedule
void StartJobSchedule();
//Cancel JobSchedule
void CancelJobSchedule();
}
Then can invoke in Xamarin Forms as follow :
async void ScheduleJob(object s, EventArgs e)
{
DependencyService.Get<IJobSchedulerService>().StartJobSchedule();
}
//Button OnClickEvent
async void CancelJob(object s, EventArgs e)
{
DependencyService.Get<IJobSchedulerService>().CancelJobSchedule();
}
Now you need to implement the IJobSchedulerService in native android .Create the JobSchedulerDependcenyService:
public class JobSchedulerDependcenyService : IJobSchedulerService
{
JobScheduler jobScheduler;
public JobSchedulerDependcenyService()
{
jobScheduler = (JobScheduler)MainActivity.Instance.GetSystemService(Android.Content.Context.JobSchedulerService);
}
public void StartJobSchedule()
{
ComponentName componentName = new ComponentName(MainActivity.Instance, Java.Lang.Class.FromType(typeof(DownloadJob)));
JobInfo jobInfo = new JobInfo.Builder(1, componentName)
.SetOverrideDeadline(0)
.Build();
//var jobScheduler = (JobScheduler)GetSystemService(JobSchedulerService);
var scheduleResult = jobScheduler.Schedule(jobInfo);
if (JobScheduler.ResultSuccess == scheduleResult)
{
var snackBar = Snackbar.Make(MainActivity.Instance.FindViewById(Android.Resource.Id.Content), "jobscheduled_success", Snackbar.LengthShort);
snackBar.Show();
}
else
{
var snackBar = Snackbar.Make(MainActivity.Instance.FindViewById(Android.Resource.Id.Content), "jobscheduled_failure", Snackbar.LengthShort);
snackBar.Show();
}
}
public void CancelJobSchedule()
{
jobScheduler.CancelAll();
}
}
Here you will find the MainActivity.Instance inside it , that's a static instance defined by self in MainActivity.
public static MainActivity Instance { set; get; }
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
Instance = this;
Xamarin.Essentials.Platform.Init(this, savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
LoadApplication(new App());
}

Xamarin Forms Service with IsolatedProcess crashes

I'm developing an Android application with Xamarin Forms that is composed of an interface and also a background service.
I need that the service works also when the interface application is closed.
If I add "IsolatedProcess = true" into the service the graphical interface still works but the service crashes.
I read a lot of posts with possible solutions but they don't work. (I tried to compile in release mode and also to remove "Use Shared Runtime" flag).
I'm compiling with Android 8.1 (Oreo) as Target Framework.
The target environment is Android 4.2.
I start the service into OnCreate method of the MainActivity class:
Intent testIntent = new Intent(this.BaseContext, typeof(TestService));
StartService(testIntent);
The service class:
[Service(IsolatedProcess = true, Exported = true, Label = "TestService")]
public class TestService : Service
{
public override IBinder OnBind(Intent intent)
{
return null;
}
public override void OnCreate()
{
base.OnCreate();
}
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
Device.StartTimer(new TimeSpan(0, 0, 40), () =>
{
//Code executed every 40 seconds
});
base.OnStartCommand(intent, flags, startId);
return StartCommandResult.Sticky;
}
public override bool StopService(Intent name)
{
return base.StopService(name);
}
}
If I remove "IsolatedProcess = true" the service works but it will be stopped when I will close the application interface process.

I solved the issue by changing the value of the attribute IsolatedProcess to true, removing the Device.StartTimer instruction and by introducing a BroadcastReceiver.
MainActivity class:
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
public static Intent testServiceIntent;
protected override void OnCreate(Bundle savedInstanceState)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate(savedInstanceState);
global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
testServiceIntent = new Intent(this.BaseContext, typeof(TestService));
LoadApplication(new App());
}
}
The service class:
[Service(IsolatedProcess = false, Exported = true, Label = "TestService")]
public class TestService : Service
{
System.Threading.Timer _timer;
public override IBinder OnBind(Intent intent)
{
return null;
}
public override void OnCreate()
{
base.OnCreate();
}
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
businessLogicMethod();
base.OnStartCommand(intent, flags, startId);
return StartCommandResult.Sticky;
}
public void businessLogicMethod()
{
//My business logic in a System.Threading.Timer
}
}
The Broadcast Receiver class:
[BroadcastReceiver]
[IntentFilter(new[] { Intent.ActionBootCompleted })]
public class TestApplicationBroadcastReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
Log.Info("TestApp", "******* Loading Application *******");
try
{
if (intent.Action.Equals(Intent.ActionBootCompleted))
{
Intent service = new Intent(context, typeof(TestService));
service.AddFlags(ActivityFlags.NewTask);
context.StartService(service);
}
}
catch (Exception ex)
{
Log.Error("TestApp", "******* Error message *******: " + ex.Message);
}
}
}
I hope that can be useful for someone.

Xamarin forms background service is killed when app is killed

I am making use of Prism in my xamarin forms project.I am also making use of background services to push long running tasks in the background.The problem is when the app is killed the service is also killed.And by "killed" I mean press home-button -> see all running apps -> swipe my app aside -> app killed .I want to keep the service alive even if the app is killed.I have read many posts which say that it can be done.However I was not able to get it working.
This is what I have tried :-
This is Android MainActivity.cs
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
try
{
global::Xamarin.Forms.Forms.Init(this, bundle);
LoadApplication(new App(new AndroidInitializer()));
WireUpLongRunningTask();
}
catch(Exception)
{
}
}
public void WireUpLongRunningTask()
{
MessagingCenter.Subscribe<StartSyncBackgroundingTask>(this, "StartSyncBackgroundingTask", message => {
var intent = new Intent(this, typeof(AndroidSyncBackgroundService));
StartService(intent);
});
}
This is AndroidSyncBackgroundService class :-
[Service]
public class AndroidSyncBackgroundService : Service
{
CancellationTokenSource _cts;
private ISyncBackgroundService _isyncBackgroundService;
private App _app => (App)Xamarin.Forms.Application.Current;
public override IBinder OnBind(Intent intent)
{
return null;
}
public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
{
_cts = new CancellationTokenSource();
Task.Run(() => {
try {
//INVOKE THE SHARED CODE
_isyncBackgroundService = _app.Container.Resolve<ISyncBackgroundService>();
_isyncBackgroundService.RunBackgroundingCode(_cts.Token).Wait();
}
catch (System.OperationCanceledException) {
}
finally {
if (_cts.IsCancellationRequested) {
var message = new CancelledTask();
Device.BeginInvokeOnMainThread(
() => MessagingCenter.Send(message, "CancelledTask")
);
}
}
}, _cts.Token);
return StartCommandResult.Sticky;
}
public override void OnDestroy()
{
if (_cts != null) {
_cts.Token.ThrowIfCancellationRequested();
_cts.Cancel();
}
StartService(new Intent("com.xamarin.AndroidSyncBackgroundService"));
base.OnDestroy();
}
public override void OnTaskRemoved(Intent rootIntent)
{
Intent restartServiceIntent = new Intent(Xamarin.Forms.Forms.Context, typeof(AndroidSyncBackgroundService));
PendingIntent restartServicePendingIntent = PendingIntent.GetService(Xamarin.Forms.Forms.Context, 1, restartServiceIntent,PendingIntentFlags.OneShot);
AlarmManager alarmService = (AlarmManager)Xamarin.Forms.Forms.Context.GetSystemService(Context.AlarmService);
alarmService.Set(
AlarmType.ElapsedRealtime,
1000,
restartServicePendingIntent);
base.OnTaskRemoved(rootIntent);
}
}
This is SyncBackgroundService class :-
public class SyncBackgroundService: ISyncBackgroundService
{
private ISqliteCallsService _iSqliteCallsService;
private IFeedBackSqliteService _feedBackSqliteService;
private ISettingApiService _isettingApiService;
private ISettingSqliteService _isettingSqliteService;
private IWebApiService _iwebApiService;
private App _app => (App)Xamarin.Forms.Application.Current;
public async Task RunBackgroundingCode(CancellationToken token)
{
_iSqliteCallsService= _app.Container.Resolve<ISqliteCallsService>();
await Task.Run(async () => {
token.ThrowIfCancellationRequested();
App.bRunningBackgroundTask = true;
await Task.Run(async () =>
{
await Task.Delay(1);
_iSqliteCallsService.ftnSaveOnlineModeXMLFormat("Offline", 0);
_iSqliteCallsService.SyncEmployeeTableData();
_iSqliteCallsService.SaveOfflineAppCommentData();
_iSqliteCallsService.SaveOfflineAdditionToFlowData();
await Task.Delay(500);
//MessagingCenter.Send<SyncBackgroundService>(this, "StopSyncBackgroundingTask");
});
}, token);
}
}
}
As can be seen in the code snippet I have made use of StartCommandResult.Sticky and still the service gets killed and does not restart.
Also i'm making use of Alarm Manager in OnTaskRemoved method,which gets fired when the app is killed according to its documentation.But in my case the service does not restart atall.Can somebody point out what is the mistake in my code? Or provide a working solution so that I can implement it in my app.
Thanks in advance!

Try this after you call StartService
if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.Kitkat)
{
PendingIntent pintent = PendingIntent.GetService(AppContext, 0, new Intent(AppContext, typeof(AndroidSyncBackgroundService )), 0);
AlarmManager alarm = (AlarmManager)AppContext.GetSystemService(Context.AlarmService);
alarm.Cancel(pintent);
}
The reason this might work is because Android schedules your service to be killed after your app is killed. Doing this removes that scheduled task.

Android Xamarin - Closed app notification

I'd like to create notificiation in my app, which is going to be showed in 10 seconds. It works well, when application is running, but when I close the application, notification is not showed. Here is my code:
My notification service:
[Service]
class NotifyEvent : IntentService
{
protected override void OnHandleIntent(Intent intent)
{
PendingIntent pIntent = PendingIntent.GetActivity(this, 0, intent, 0);
Notification.Builder builder = new Notification.Builder(this);
builder.SetContentTitle(Resources.GetString(Resource.String.NotifikaceNadpis));
builder.SetContentText(Resources.GetString(Resource.String.NotifikaceText));
builder.SetSmallIcon(Resource.Drawable.Icon);
builder.SetPriority(1);
builder.SetDefaults(NotificationDefaults.Sound | NotificationDefaults.Vibrate);
builder.SetWhen(Java.Lang.JavaSystem.CurrentTimeMillis());
Notification notifikace = builder.Build();
NotificationManager notificationManager = GetSystemService(Context.NotificationService) as NotificationManager;
const int notificationId = 0;
notificationManager.Notify(notificationId, notifikace);
}
}
Class, which starts notification:
public class Notificator
{
public void ShowNotification(Context context)
{
Intent intent = new Intent(context, typeof(NotifyEvent));
var pendingServiceIntent = PendingIntent.GetService(context, 0, intent, PendingIntentFlags.UpdateCurrent);
AlarmManager alarm = (AlarmManager)context.GetSystemService(Context.AlarmService);
alarm.Set(AlarmType.ElapsedRealtimeWakeup, SystemClock.ElapsedRealtime() + 10000, pendingServiceIntent);
}
}
Method in activity:
Notificator not = new Notificator();
not.ShowNotification(this);
My Activity:
[Activity(Label = "Nastavení")]
public class SettingsActivity : Activity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your application here
SetContentView(Resource.Layout.Settings);
Button vynulovatButton = FindViewById<Button>(Resource.Id.buttonRestartDne);
vynulovatButton.Click += VynulovatDen;
}
...
protected void VynulovatDen(object sender, EventArgs e)
{
Notificator not = new Notificator();
not.ShowNotification(this);
}
}
Thanks for every help.

you can try this.
protected override void OnDestroy()
{
Notificator not = new Notificator();
not.ShowNotification(this);
base.OnDestroy();
}

You should keep your service alive when you destroy your application.
add return StartCommandResult.Sticky; in the OnStartCommand method.
start the service OnTaskRemoved function.
Create your service with the Service interface, the IntentService is for Time-consuming operation.
class NotifyEvent : Service
{
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
new Task(() => {
PendingIntent pIntent = PendingIntent.GetActivity(this, 0, intent, 0);
Notification.Builder builder = new Notification.Builder(this);
builder.SetContentTitle("hello");
builder.SetContentText("hello");
builder.SetSmallIcon(Resource.Drawable.Icon);
builder.SetPriority(1);
builder.SetDefaults(NotificationDefaults.Sound | NotificationDefaults.Vibrate);
builder.SetWhen(Java.Lang.JavaSystem.CurrentTimeMillis());
Notification notifikace = builder.Build();
NotificationManager notificationManager = GetSystemService(Context.NotificationService) as NotificationManager;
const int notificationId = 0;
notificationManager.Notify(notificationId, notifikace);
}).Start();
return StartCommandResult.Sticky;
}
public override IBinder OnBind(Intent intent)
{
return null;
}
public override void OnTaskRemoved(Intent rootIntent)
{
Intent restartService = new Intent(ApplicationContext, typeof(NotifyEvent));
restartService.SetPackage(PackageName);
var pendingServiceIntent = PendingIntent.GetService(ApplicationContext, 0, restartService, PendingIntentFlags.UpdateCurrent);
AlarmManager alarm = (AlarmManager)ApplicationContext.GetSystemService(Context.AlarmService);
alarm.Set(AlarmType.ElapsedRealtime, SystemClock.ElapsedRealtime() + 1000, pendingServiceIntent);
System.Console.WriteLine("service OnTaskRemoved");
base.OnTaskRemoved(rootIntent);
}
}