title: Store some Core Data entities in SQL lite but others only in memory of same managed object type
body: <p>I can't find a solution for my following case. It is about a chat implementation, where I store everything in core data to not need to download everything again every time.</p>
  
  <p>This means that I am storing all existing conversations and their participating users. But when it comes to searching for users to create or extend a conversation, the issue begins. When the user is searching for other users the search results are all stored in core data. Which is nice, because the user can use theses cached search results in the next search and doesn't need to wait for the server to respond to the search query.</p>
  
  <p>But it can happen that a user has been deleted on server side, so the user shouldn't appear anymore in the search results. But I may already have stored that user in the core data persistent (SQL lite) store.</p>
  
  <p>What I want to achieve is:</p>
  
  <ul>
  <li>Store every user by default in the persistent (SQL lite) store</li>
  <li>Users that were only appearing in the search results should only be stored in an in-memory storage, so that the entities are gone after app has been terminated</li>
  </ul>
  
  <p>But of course I still want to combine both storages when displaying the search results. Is there any way how I can tell a NSManagedObject to 'volatile'? Or do I need to somehow combine two different NSPersistentStoreCoordinator (one with SQL lite storage, the other with in-memory only)?</p>