title: Custom code execution after light weight migration of particular version
body: <p>I have 2 object models in Core Data (say v1 and v2). This migration is eligible for light weight migration. Now, I want to execute custom code after the migration but only when the migration is from v1 to v2. Later on if I introduce v3, I don't want the custom code to get executed.</p>
  
  <p>Is there a way to do this?</p>
  
  <p>Thanks in advance,
  Anupam</p>