Xamarin example to receive url or text from other applications. For example when you are on the youtube app and click share.

MainActivity.cs

using Android.App;
using Android.Widget;
using Android.OS;
using Android.Content;
using System.Text;
using System;

namespace AndroidDataReceiver
{
    [Activity(Label = "AndroidDataReceiver", MainLauncher = true,  LaunchMode = Android.Content.PM.LaunchMode.SingleTop )]
    [BroadcastReceiver]
    [IntentFilter(new[] { Intent.ActionSend }, Categories = new[] {
    Intent.CategoryDefault,
    Intent.CategoryBrowsable
}, DataMimeType = "text/plain")]
    public class MainActivity : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);


            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);
            if (!String.IsNullOrEmpty(Intent.GetStringExtra(Intent.ExtraText)))
            {
                string url = Intent.GetStringExtra(Intent.ExtraText) ?? "url not available";
                Toast.MakeText(this, url, ToastLength.Long).Show();            
            }
        }

    }
}