How to check for network_provider and gps_provider in Xamarin forms?

Question

I am using Xamarin.Forms and working with a project that will run in Android and Iphone. My project structure (if that information is useful?) are three projects "MyApp", "MyApp.Android" and "MyApp.iOS" inside the same solution.

Right now I am using different plugins such as Xam.Plugin.Geolocator and Plugin.Geofencing.Eddy in order to use Geofencing, but I am facing some problems (as stated in this other question Geofence for xamarin crossplatform).

Right now I want to check if the geofence will be able to work, checking if GPS_PROVIDER and NETWORK_PROVIDER are available, how could I achieve that? Right now I only can check if Location is enabled, but not which provider.

public bool IsLocationAvailable()
            {
                if (!CrossGeolocator.IsSupported)
                    return false;
                if (!CrossGeolocator.Current.IsGeolocationEnabled)
                    return false;
                if (!CrossGeolocator.Current.IsGeolocationAvailable)
                    return false;
                if (!CrossGeofencing.IsSupported)
                    return false;
                return true;
            }

Right now if location provider is set to "GPS only" it throwns an error because of this, but I am not sure how to catch it and handle it. I have seen some other examples and questions but are exclusively for android and I am not sure how to implement those if I am already using those plugins and working mainly on the xamarin forms project (aka "MyApp") instead of the android one ("MyApp.Android")

Sorry for the big image, I am not sure how to resize it!

Answer 1

You can always run platform specific code in your shared project, "MyApp", using Xamarin.Forms Dependency Service.

The basic idea is that you create an interface in your shared project, lets call it IGetLocationProvider:

public interface IGetLocationProvider {
    string GetProvider (); 
}

Then in the Android,"MyApp.Android", and/or iOS, "MyApp.iOS" app projects, you implement the interface in a class and add the Dependency attribute to the class. But first you will need access to the Android app context. The easiest way to have this available globally in the Android app project is to add a static variable to the MainActivity class and set it in OnCreate:

public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    public static Context Context;
    ... 
    protected override void OnCreate(Bundle savedInstanceState)
    {
        ...
        MainActivity.Context = this;

    }
}

Now here is the platform specific Dependency Service for Android that will return a string with comma separated available location providers:

using System;
using GetLP.Droid;
using Xamarin.Forms;
using Android.Locations;

[assembly: Dependency(typeof(GetLocationProvider))]
namespace GetLP.Droid
{
    public class GetLocationProvider : IGetLocationProvider
    {
        public string GetProvider()
        {
            string returnString = "";

            LocationManager manager = (LocationManager)MainActivity.Context.GetSystemService(Android.Content.Context.LocationService);
            bool gpsProviderEnabled = manager.IsProviderEnabled(LocationManager.GpsProvider);
            bool networkProviderEnabled = manager.IsProviderEnabled(LocationManager.NetworkProvider);
            bool passiveProviderEnabled = manager.IsProviderEnabled(LocationManager.PassiveProvider);

            returnString += gpsProviderEnabled ? "GPS," : ",";
            returnString += networkProviderEnabled ? "Network," : ",";
            returnString += passiveProviderEnabled ? "Passive" : "";

            return returnString;
        }
    }
}

Now you can call GetProvider from your shared code:

string providers = DependencyService.Get<IGetLocationProvider>().GetProvider();

The variable providers will be a comma separated string of the available providers, e.g. if GSP and Passive are available the string will be "GPS,,Passive" and if Network and Passive are available the string will be ",Network,Passive". Of course you can change the GetProvider to return an array or List or whatever you want, just make sure it is something that is available on all platforms, i.e. don't return a LocationManager as that is Android specific type.

For iOS, there is nothing similar. iOS decides what methods to use to get the location and what the OS uses is not available to an app developer when getting the location, so you only want to call this dependency service when running on Android.