Core Data - How to check if a managed object's properties have been deallocated?

Question

I've created a program that uses core data and it works beautifully.

I've since attempted to move all my core data methods calls and fetch routines into a class that is self contained. My main program then instantiates that class and makes some basic method calls into that class, and the class then does all the core data stuff behind the scenes. What I'm running into, is that sometimes I'll find that when I grab a managed object from the context, I'll have a valid object, but its properties have been deallocated, and I'll cause a crash. I've played with the zombies and looked for memory leaks, and what I have gathered is it seems that the run loop is probably responsible for deallocating the memory, but I'm not sure.

Is there a way to determine if that memory has been deallocated and force the core data to get it back if I need to access it? My managedObjectContext never gets deallocated, and the fetchedResultsController never does, either.

I thought maybe I needed to use the [managedObjectContext refreshObject:mergeData:] method, or the [managedObjectContext setRetainsRegisteredObjects:] method. Although, I'm under the impression that last one may not be the best bet since it will be more memory intensive (from what I understand).

These errors only popped up when I moved the core data calls into another class file, and they are random when they show up.

Any insight would be appreciated.

-Ryan

Answer 1

Sounds to me like you are not retaining objects you want to keep hanging around. If you are doing something like this:

NSArray *array = [moc executeFetchRequest:request error:&error];

you do not own the returned array and it will most likely disappear when the current autorelease pool is drained. This will occur when the run loop finishes processing the current event.

All this is speculation. If you want a proper answer, you need to post your code.

Answer 2

It's hard to know what the problem is based on your description, but you might want to look at the Core Data memory management guide. You shouldn't have to worry about memory management for managed objects and their entities (they're fetched and faulted automatically). When you talk about "properties," do you mean custom properties backed by ivars? If so, these should be released in didTurnIntoFault and allocd as needed (probably in the accessor).