Creating a custom renderer to extend the map in the iOS app

First, we will create a custom renderer for iOS by going through the following steps. Because we want to extend its functionality, we will use MapRenderer as a base class:

1. Create a folder called Renderers in the MeTracker.iOS project.
2. Create a new class in this folder called CustomMapRenderer.
3. Add MapRenderer as a base class.
4. Add the ExportRenderer attribute, as shown in the following code:

 using System.ComponentModel;
 using System.Linq;
 using MapKit;
 using MeTracker.Controls;
 using MeTracker.iOS.Renderers;
 using Xamarin.Forms;
 using Xamarin.Forms.Maps.iOS;
 using Xamarin.Forms.Platform.iOS; 

  [assembly:ExportRenderer(typeof(CustomMap),
  typeof(CustomMapRenderer))]
  namespace MeTracker.iOS.Renderers
{
     public class CustomMapRenderer : MapRenderer
     { 
     }
}

When a property changes for the control that we are writing a custom renderer for, the OnElementPropertyChanged method is called. This method...