title: Xamarin WebView iOS detect Scrolling event
body: <p>Setup: I'm using Xamarin (and Xamarin.Forms) developing an app with an embedded browser.</p>
  
  <p>My issue:
  I have a WebView and I'm trying to detect when a user is scrolling, and whether it is Up or Down.</p>
  
  <p>So far, I have created a Custom WebViewRenderer for the iOS-project. But how does one subscribe to scrolling events?
  Googling makes me believe that overriding the WebViewRenderer's</p>
  
  <pre><code>OnElementChanged(VisualElementChangedEventArgs e)
  </code></pre>
  
  <p>should be the right way, but I can't seem to find any documentation/leads on how to go further. 
  Does anyone know, or can point me in the right direction?</p>