Will you be updating this when MacOS 10.12 releases, or will that be a fourth edition? (I have the 2nd edition.) It looks like you have some good new info I could use. Especially on threading and migration. I’ve never gotten migration down right. Also, how to get rid old development models.
Our Mac app, iQPresenter (to be released shortly) uses three instance types of the same CoreData model, i.e, one for each document, one for the application, one for each object library document (commonly used objects and templates).
Our media files are kept in a separate folder with the database in a file wrapper. We use a “File” object to manage these and they are shared objects, reference counted (actually, the sum of various reference counts) so they only get deleted when no object references remain. I wish CoreData had a built-in way to handle this.