NSFetchRequest *oldFetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *oldEntryEntity = [NSEntityDescription entityForName:@"Entry"
                                                          inManagedObjectContext:oldMOC];
[oldFetchRequest setEntity:oldEntryEntity];
[oldFetchRequest setFetchBatchSize:10];
NSArray *entrys = [oldMOC executeFetchRequest:oldFetchRequest error:nil];

for (NSInteger index = 0; index < entrys.count; ++index) {

    Entry *entry = [entrys objectAtIndex:index];

    NSOrderedSet *oldMediaSet = [entry valueForKey:@"media"];

    for (Media *media in oldMediaSet) {

        @autorelease {

            [media valueForKey:@"originalImage"];

        }

    }

}