title: How to trigger code once after update in Xamarin
body: <p>I have a Xamarin.Forms application for iOS and Android which is about to recieve som larger changes. To migrate the current data stored in the app, I would like to run some "migration code" as soon as the app is updated - is this possible?</p>
  
  <p>Is there any event or alike in Xamarin.Forms which allows me to <strong>run a piece of migration code only once when the app has been updated?</strong></p>