PushReceiver.cs

using System;
using System.Threading.Tasks;
using Android.App;
using Android.Content;
using Android.Media;

namespace MemberApp.Droid
{
	public class PushReceiver : BroadcastReceiver
	{
        public async override void OnReceive(Context context, Intent intent)
        {
            String custom = intent.GetStringExtra("custom").ToString();
            // Check here to see if the payload indicates that the sound should be played
            await PlaySound(context);
        }

        async Task PlaySound(Context context)
        {
            var am = (AudioManager)Application.Context.GetSystemService(Context.AudioService);
            var tcs = new TaskCompletionSource<object>();
            int currentVolume = am.GetStreamVolume(Stream.Music);
            int maxVolume = am.GetStreamMaxVolume(Stream.Music);
            var handler = new EventHandler((sender, args) => tcs.TrySetResult(null));
            MediaPlayer mediaPlayer = null;

            try
            {
                mediaPlayer = MediaPlayer.Create(context, Resource.Raw.emergency);
                am.SetStreamVolume(Stream.Music, maxVolume, VolumeNotificationFlags.PlaySound);
                mediaPlayer.Completion += handler;
                mediaPlayer.Start();
                await tcs.Task.ConfigureAwait(false);
            }
            finally
            {
                if (mediaPlayer != null)
                {
                    am.SetStreamVolume(Stream.Music, currentVolume, VolumeNotificationFlags.PlaySound);
                    mediaPlayer.Completion -= handler;
                }
            }
        }
    }
}