An example of the AndroidScheduler subscribing an observable sequence on the UI Thread

gistfile1.cs

namespace RxM4AExampleSolution
{
    using System;
    using System.Reactive.Linq;
    using System.Reactive.Mono.Android;
    using System.Threading;
    using System.Threading.Tasks;
    using Android.App;
    using Android.OS;
    using Android.Widget;

    /// <summary>
    /// Example implementation of RxM4A
    /// </summary>
    [Activity(Label = "RxM4AExampleSolution", MainLauncher = true, Icon = "@drawable/icon")]
    public class Activity1 : Activity
    {
        /// <summary>
        /// The interval observable that is setup in a non ui thread
        /// </summary>
        private IObservable<long> obs1;

        /// <summary>
        /// The interval observable that is setup on the ui thread
        /// </summary>
        private IObservable<long> obs2;

        /// <summary>
        /// OnCreate Override
        /// </summary>
        /// <param name="bundle">The bundle</param>
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            this.SetContentView(Resource.Layout.Main);
            FindViewById<TextView>(Resource.Id.activityThread).Text = Thread.CurrentThread.ManagedThreadId.ToString();

            this.obs2 = Observable.Interval(TimeSpan.FromSeconds(3)).ObserveOn(AndroidScheduler.UIContext(this));

            obs2.Subscribe(x =>
            {
                try
                {
                    FindViewById<TextView>(Resource.Id.handlerThread2).Text = Thread.CurrentThread.ManagedThreadId.ToString();
                    FindViewById<TextView>(Resource.Id.interval2).Text = x.ToString();
                }
                catch (Exception ex)
                {
                    var exs = ex.ToString();
                }
            });

            Task.Factory.StartNew(this.SetupObservable);
        }

        /// <summary>
        /// A delegate that setups an observable subscription from another thread
        /// </summary>
        private void SetupObservable()
        {
            this.obs1 = Observable.Interval(TimeSpan.FromSeconds(3)).ObserveOn(AndroidScheduler.UIContext(this));

            // Get our button from the layout resource,
            // and attach an event to it
            Button button = FindViewById<Button>(Resource.Id.MyButton);

            button.Click += (sender, args) => 
            {
                Toast.MakeText(this, "Starting Subscription", ToastLength.Long).Show();

                obs1.Subscribe(x =>
                {
                    try
                    {
                        FindViewById<TextView>(Resource.Id.handlerThread).Text = Thread.CurrentThread.ManagedThreadId.ToString();
                        FindViewById<TextView>(Resource.Id.interval).Text = x.ToString();
                    }
                    catch (Exception ex)
                    {
                        var exs = ex.ToString();
                    }
                });
            };
        }
    }
}