Adding native orientation events

Our next step is to add the notifications that are going to fire every time an orientation occurs. These events will come from the native side, so in order to have these pass down to our Xamarin.Forms project, we are going to use the static events on the OrientationPage.

Let's start with the iOS project. Open the AppDelegate.cs file and add the following function:

        public override void DidChangeStatusBarOrientation(UIApplication application, UIInterfaceOrientation oldStatusBarOrientation) 
        { 
            // change listview opacity based upon orientation 
            switch (UIApplication.SharedApplication.StatusBarOrientation) 
            { 
                case UIInterfaceOrientation.Portrait: 
                case UIInterfaceOrientation.PortraitUpsideDown: 
                    OrientationPage.NotifyOrientationChange(Orientation.Portrait); 
                    break; 
                case UIInterfaceOrientation.LandscapeLeft: 
      ...