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Background Location Tracking for Android with Xamarin.Forms

You can do it with device timer. The timer will run periodically & will check for location updates and notify if location updated. I have used Xam.Plugins.Notifier to generate local notification on location update.

Here is the code for it :

public partial class MainPage : ContentPage
{
    Location oldLocation = null;
    CancellationTokenSource cts;
    public MainPage()
    {
        InitializeComponent();
        Device.StartTimer(TimeSpan.FromSeconds(10), () =>
        {
            GetCurrentLocation();
            return true;
        });
    }

    protected async override void OnAppearing()
    {
        base.OnAppearing();
        await GetCurrentLocation();
    }

    async Task GetCurrentLocation()
    {
        try
        {
            var request = new GeolocationRequest(GeolocationAccuracy.Medium, TimeSpan.FromSeconds(10));
            cts = new CancellationTokenSource();
            var location = await Geolocation.GetLocationAsync(request, cts.Token);

            if (location != null)
            {
                Debug.WriteLine($"Latitude: {location.Latitude}, Longitude: {location.Longitude}, Altitude: {location.Altitude}");
                if (oldLocation == null)
                {
                    oldLocation = location;
                    map.MoveToRegion(MapSpan.FromCenterAndRadius(
                   new Position(location.Latitude, location.Longitude), Distance.FromMiles(0.3)));
                }
                if (location.Latitude != oldLocation.Latitude || location.Longitude != oldLocation.Longitude)
                {
                    map.MoveToRegion(MapSpan.FromCenterAndRadius(
                   new Position(location.Latitude, location.Longitude), Distance.FromMiles(0.3)));

                    oldLocation = location;
                    double zoomLevel = 0.5;
                    double latlongDegrees = 360 / (Math.Pow(2, zoomLevel));
                    if (map.VisibleRegion != null)
                    {
                        map.MoveToRegion(new MapSpan(map.VisibleRegion.Center, latlongDegrees, latlongDegrees));
                    }

                    var placemarks = await Geocoding.GetPlacemarksAsync(location.Latitude, location.Longitude);
                    var placemark = placemarks?.FirstOrDefault();
                    if (placemark != null)

                    {
                        var geocodeAddress =
                            $"AdminArea:       {placemark.AdminArea}\n" +
                            $"CountryCode:     {placemark.CountryCode}\n" +
                            $"CountryName:     {placemark.CountryName}\n" +
                            $"FeatureName:     {placemark.FeatureName}\n" +
                            $"Locality:        {placemark.Locality}\n" +
                            $"PostalCode:      {placemark.PostalCode}\n" +
                            $"SubAdminArea:    {placemark.SubAdminArea}\n" +
                            $"SubLocality:     {placemark.SubLocality}\n" +
                            $"SubThoroughfare: {placemark.SubThoroughfare}\n" +
                            $"Location :       {placemark.Location}\n" +
                            $"Thoroughfare:    {placemark.Thoroughfare}\n";

                        Debug.WriteLine(geocodeAddress);
                    }
                    
                    CrossLocalNotifications.Current.Show("Location Updated", "You checked in to " + placemark.FeatureName + " " + placemark.Locality + " " + placemark.SubLocality, 101, DateTime.Now.AddSeconds(5));
                }
            }
        }
        catch (FeatureNotSupportedException)
        {
            // Handle not supported on device exception
        }
        catch (FeatureNotEnabledException)
        {
            // Handle not enabled on device exception
        }
        catch (PermissionException)
        {
            // Handle permission exception
        }
        catch (Exception)
        {
            // Unable to get location
        }
    }
}