Xamarin.Forms : Get Notified for device orientation changes with MessagingCenter

AppDelegate.cs

using System;
using System.Collections.Generic;
using System.Linq;

using MonoTouch.Foundation;
using MonoTouch.UIKit;

using Xamarin.Forms;
using System.Net;

using MyNamespace.Models;

namespace MyNamespace.iOS
{
    [Register("AppDelegate")]
    public partial class AppDelegate : UIApplicationDelegate
    {
        UIWindow window;
        RootPage _root;
 
        public override void DidChangeStatusBarOrientation(UIApplication application, UIInterfaceOrientation oldStatusBarOrientation)
        {           
            var currentOrientation = UIApplication.SharedApplication.StatusBarOrientation;
            bool isPortrait = currentOrientation == UIInterfaceOrientation.Portrait || currentOrientation == UIInterfaceOrientation.PortraitUpsideDown;
            SendOrientationMessage(!isPortrait);
        }

        static void SendOrientationMessage(bool isLandscape)
        {
            var msg = new DeviceOrientationChangeMessage()
            {
                Orientation = isLandscape ? DeviceOrientation.Landscape : DeviceOrientation.Portrait
            };
            MessagingCenter.Send<DeviceOrientationChangeMessage>(msg, DeviceOrientationChangeMessage.MessageId);
        }

        public override bool FinishedLaunching(UIApplication app, NSDictionary options)
        {
            window = new UIWindow(UIScreen.MainScreen.Bounds);

            Forms.Init();
 
            window.RootViewController = BuildView();
            window.MakeKeyAndVisible();

            return true;
        }

      
        private UINavigationController BuildView()
        {
            _root = new RootPage();
            var controller = _root.CreateViewController();
            UINavigationController nav = new UINavigationController(controller);

            nav.SetNavigationBarHidden(true, false);

            return nav;
        }
       
    }
}

DeviceOrientation.cs

using System;

namespace MyNamespace
{
    public enum DeviceOrientation
    {
       Landscape,
        Portrait
    }
}

DeviceOrientationChangeMessage.cs

using System;

namespace MyNamespace
{
    public class DeviceOrientationChangeMessage
    {
        public DeviceOrientation Orientation
        {
            get;
            set;
        }

        public static string MessageId
        {
            get
            { 
                return "OrientationChangeMessage";
            }
        }
    }
}

MainActivity.cs

using System;
using System.Linq;
using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;

using Xamarin.Forms.Platform.Android;
using System.Net;

using Xamarin.Forms;
using Android.Content.Res;


namespace MyNamespace.Android
{
  [Activity (Label = "MyApp", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
  public class MainActivity : AndroidActivity
  {
    protected override void OnCreate (Bundle bundle)
    {
            base.OnCreate (bundle);
            Xamarin.Forms.Forms.Init (this, bundle);
            SetPage (BuildView());
    }

    public override void OnConfigurationChanged (Configuration newConfig)
    {
      base.OnConfigurationChanged (newConfig);
            bool isLandscape = newConfig.Orientation == global::Android.Content.Res.Orientation.Landscape;
            RootPage.Current.IsLandscape = isLandscape;

            SendOrientationMessage(isLandscape);
    }

    static void SendOrientationMessage(bool isLandscape)
    {
        var msg = new DeviceOrientationChangeMessage() {
            Orientation = isLandscape ? DeviceOrientation.Landscape : DeviceOrientation.Portrait
        };
        MessagingCenter.Send<DeviceOrientationChangeMessage>(msg, DeviceOrientationChangeMessage.MessageId);
    }

    static Page BuildView()
    {
        return new RootPage();
    }
  }
}