title: Core Data parent Entity
body: <p>I have an abstract Entity A, I also have two Entities whom's parent is Entity A.
  Each child has different relationships to other Entities.</p>
  
  <p>I am trying to fetch all child Entities of Entity A, who's isPublic boolean value is YES.</p>
  
  <p>I've had trouble with fetching subclassed Entities in the past in relation to fetching, and I'm sure I'm just not doing it correctly.</p>
  
  <p>So we could say for example that :
  • Entity A is "Document", 
  • Entity B is "Poem",
  • Entity C is "Article"</p>
  
  <p>All poems and articles subclass document, and document has a property called isBookmarked, the suer can bookmark a poem or article, and I need a way of fetching all documents that are bookmarked. Entities B and C need to be independent because of other relationships that they own.</p>
  
  <p>I want to use NSFetchedResultsController for optimal Core Data and UITableView performance, and I'm struggling to fetch a mix of poems and articles.</p>
  
  <p>What fetch request would give me a mix of poems and articles ?</p>
  
  <p><img src="https://i.stack.imgur.com/biMUW.jpg" alt="enter image description here"></p>