All Component in Xamarin

BackGround Service Get Location Xamrin Forms

1) PCL:

using System;

using Xamarin.Forms;

namespace myapp
{
    public class LongRunningPage : ContentPage
    {
        Label lbl;
        public LongRunningPage()
        {
            Button startbtn = new Button();
            startbtn.Text = "Start";

            Button stopbtn = new Button();
            stopbtn.Text = "Stop";

            lbl = new Label();
            lbl.Text = "";

            Content = new StackLayout
            {
                Spacing=20,
                Children = {
                    startbtn,stopbtn,lbl
                }
            };
            startbtn.Clicked += (s, e) => {
                var message = new StartLongRunningTaskMessage();
                MessagingCenter.Send(message, "StartLongRunningTaskMessage");
            };
            stopbtn.Clicked += (s, e) => {
                var message = new StopLongRunningTaskMessage ();
                MessagingCenter.Send (message, "StopLongRunningTaskMessage");
            };
               



            HandleReceivedMessages();
        }
        void HandleReceivedMessages()
        {
            MessagingCenter.Subscribe<TickedMessage>(this, "TickedMessage", message => {
                Device.BeginInvokeOnMainThread(() => {
                    lbl.Text = message.lat.ToString() + "\n" + message.lon.ToString();
                });
            });

            MessagingCenter.Subscribe<CancelledMessage>(this, "CancelledMessage", message => {
                Device.BeginInvokeOnMainThread(() => {
                    lbl.Text = "Cancelled";
                });
            });
        }
    }
}

2)Methods:

public class StartLongRunningTaskMessage
    {
       
    }

 public class StopLongRunningTaskMessage
    {
       
    }

 public class CancelledMessage
    {
      
    }

public class TickedMessage
    {
        public string Message { get; set; }

        public string lat { get; set; }

        public string lon { get; set; }
    }

using Plugin.Geolocator;

 public class TaskCounter
    {
        public async Task RunCounter(CancellationToken token)
        {
            await Task.Run(async () => {

                for (long i = 0; i < long.MaxValue; i++)
                {
                    token.ThrowIfCancellationRequested();

                    await Task.Delay(2000);

                    var locator = CrossGeolocator.Current;
                    locator.DesiredAccuracy = 50;
                    var position = await locator.GetPositionAsync(TimeSpan.FromSeconds(1));
                    var lat = position.Latitude;
                    var longt = position.Longitude;
                    var message = new TickedMessage
                    {
                        Message = i.ToString(),
                        lat = lat.ToString(),
                        lon = longt.ToString()


                    };

                    Device.BeginInvokeOnMainThread(() => {
                        DependencyService.Get<IMessage>().ShortAlert(message.lat + message.lon);
                        MessagingCenter.Send<TickedMessage>(message, "TickedMessage");
                    });
                }
            }, token);
        }
    }

3)Android:

i)service

using Android.App;
using Android.Content;
using System.Threading.Tasks;
using Android.OS;
using System.Threading;
using Xamarin.Forms;
using Orbishealth_patient.Test;
namespace myapp
{
    [Service]
    public class LongRunningTaskService : Service
    {
        CancellationTokenSource _cts;

        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
                    var counter = new TaskCounter();
                    counter.RunCounter(_cts.Token).Wait();
                }
                catch (OperationCanceledException)
                {
                }
                finally
                {
                    if (_cts.IsCancellationRequested)
                    {
                        var message = new CancelledMessage();
                        Device.BeginInvokeOnMainThread(
                            () => MessagingCenter.Send(message, "CancelledMessage")
                        );
                    }
                }

            }, _cts.Token);

            return StartCommandResult.Sticky;
        }

        public override void OnDestroy()
        {
            if (_cts != null)
            {
                _cts.Token.ThrowIfCancellationRequested();

                _cts.Cancel();
            }
            base.OnDestroy();
        }
    }
}

ii)mainactivity:

using System;

using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using Messier16.Forms.Android.Controls;
using Plugin.Permissions;
using Xamarin.Forms;
using myapp;


namespace myapp.Droid
{
    [Activity(Label = "Orbishealth_patient.Droid", Icon = "@drawable/icon", Theme = "@style/MyTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        protected override void OnCreate(Bundle bundle)
        {
           

            TabLayoutResource = Resource.Layout.Tabbar;
            ToolbarResource = Resource.Layout.Toolbar;

           
            base.OnCreate(bundle);

            global::Xamarin.Forms.Forms.Init(this, bundle);
           
            LoadApplication(new App());
            WireUpLongRunningTask();
        }
        void WireUpLongRunningTask()
        {
            MessagingCenter.Subscribe<StartLongRunningTaskMessage>(this, "StartLongRunningTaskMessage", message => {
                var intent = new Intent(this, typeof(LongRunningTaskService));
                StartService(intent);
            });

            MessagingCenter.Subscribe<StopLongRunningTaskMessage>(this, "StopLongRunningTaskMessage", message => {
                var intent = new Intent(this, typeof(LongRunningTaskService));
                StopService(intent);
            });
        }
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
        {
            PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }
}