title: Is NSDocument and CoreData a possible combination, or is NSPersistentDocument the only way?
body: <p>I'm making an application which creates course timetables for people at my school. This is the rough design I had in mind for the application:</p>
  
  <p>I'd like my NSDocument subclass to represent an individual's timetable. The idea is that they open up a document, and can add courses from a pool to their timetable, then save, share, open, etc. So the timetable will be stored in an external file, chosen by the user.</p>
  
  <p>I'd like to use CoreData to store all the courses from which students can choose. These will not be altered with the creation and editing of timetables, but instead, likely only on launch of the application, when it checks for updates to the course info.</p>
  
  <p>This seems to be the logical way to structure my app. The problem is, when I create an NSDocument-based application and check the <code>use CoreData</code> box, instead of making it an NSDocument-based app with CoreData facilities, it makes it an NSPersistentDocument-based app.</p>
  
  <p>I don't think this is the behaviour I want. Is there a way to use CoreData, but still have an NSDocument-based application? Or is NSPersistentDocument what I should be using after all? Am I misunderstanding the whole NS*Document business? Do you have any advice for my application's structure?</p>
  
  <p>Thanks for any help!</p>