I am using CoreData in my app and i have a set of "Card" entities. A player can have more than one of the same card in his deck (it is still the same card pulled from the database but added two times to an array).
My problem occurs when I want to modify an aspect of one of the duplicate cards. They are all subclassed NSManagedObjects which have some custom properties on them (which are not saved onto the database). For example when I set one of the custom properties on one card in the array it is also changed in the other same card in the array because the entityForName:inManagedObjectContext: returns the same object and does not load a new one.
Basically what I need is that each time entityForName:inManagedObjectContext: is called I get a new instance of the same entity so that when I modify a custom property in one it is not also modified in the other. I have already tried using [entity copy] if the entity has already been created but it does not work.
Thank you in advance for your help!
Core Data is a persistent store, not a database. So it's reason detre is ensuring that you get exactly the same object out, no matter how many times you ask for it. Those aren't snapshots from the database as they might be if you wrote some custom SQL code, those are the actual live objects.
With that in mind, what you need to do is either configure your Core Data schema to match your logical schema — I guess you'd have, say, CardInstance, with a one-to-many relationship with Card, and you'd create CardInstances for when you pulled a card from the deck — or write some code to read from a fetched Card into a snapshot object, exactly as if you were working manually with SQL or whatever.