title: OnAppearing different on iOS and Android
body: <p>I have found that on iOS, OnAppearing is called when the page literally appears on the screen, whereas on Android, it's called when it's created.</p>
  
  <p>I'm using this event to lazily construct an expensive to construct view but obviously the Android behaviour defeats this.</p>
  
  <p>Is there some way of knowing on Android when a screen literally appears on the screen?</p>