title: What do I have to do to get Core Data to automatically migrate models?
body: <p>I have read the documentation about automatic /lightweight migration for Core Data models - but I am having problems implementing it.</p>
  
  <p>As I understand it the application should notice that the model it has and the model that exists on a device already are not the same. If you have only added attributes or relationships and similar simple changes then the model should be upgraded automatically.</p>
  
  <p>Any pointers - do I need to set something in Xcode?</p>