valueForKey on data NSManagedObject not releasing memory - iphone

Question

I want to deal with a data attribute, named originalImage in every Media entity in the store.
The problem is that despite the autoreleasing, memory builds up every time it's accessed via valueForKey, and eventually the app crashes. Or perhaps it's loading large individual NSData items which is the problem, but Instruments shows it to be a steadily inclining graph of memory usage, until it eventually gives me a memory warning and then crashes.
I haven't started on the rest of the code for this yet, so i'm not performing some hidden task that i'm not showing you.
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Media"
inManagedObjectContext:[self managedObjectContext]];
[request setEntity:entity];
[request setFetchBatchSize:10];
NSArray *mediaItems = [[self managedObjectContext] executeFetchRequest:request error:nil];
for (NSManagedObject *media in mediaItems) {
#autoreleasepool {
[media valueForKey:#"originalImage"];
}
}
EDIT: Today it seems that even just mentioning the NSManagedObject media is enough to cause this media leak. So even without the valueForKey line, i have a leak. I've tried this:
while (i < count) {
#autoreleasepool {
NSManagedObject *media = [mediaItems objectAtIndex:i];
[[self managedObjectContext] refreshObject:media mergeChanges:NO];
NSLog(#"i: %i", i);
i++;
}
}
This also didn't work, and crashed at the same point.

Answer 1

Did you try something like:
for(int i=0;i<[mediaItems count]; i++) {
#autoreleasepool {
NSManagedObject *media = [mediaItems objectAtIndex:i];
[media valueForKey:#"originalImage"];
}
}
Maybe this way "media" gets released properly at every loop.
(Sorry, I put this on a comment. I'm new on SO and not enough rep.)