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I have a core data project that has Books and Authors. In the data model Authors has a to-many relationship to Books and Books has a 1-1 relationship with Authors. I'm trying to pull all Books that do not have an Author. No matter how I try it, no results are returned. In my predicate I've also tried = NIL, == nil, == NIL. Any suggestions would be appreciated. // fetch all books without authors - (NSMutableArray *)fetchOrphanedBooks { NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Book" inManagedObjectContext:self.managedObjectContext]; [fetchRequest setEntity:entity]; [fetchRequest setFetchBatchSize:20]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"author == nil"]; [fetchRequest setPredicate:predicate]; NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; NSString *sectionKey = @"name";//nil; NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:sectionKey cacheName:nil]; BOOL success = [aFetchedResultsController performFetch:nil]; NSMutableArray *orphans = nil; // this is always 0 NSLog(@"Orphans found: %i", aFetchedResultsController.fetchedObjects.count); if (aFetchedResultsController.fetchedObjects.count > 0) { orphans = [[NSMutableArray alloc] init]; for (Book *book in aFetchedResultsController.fetchedObjects) { if (book.author == nil) { [orphans addObject:book]; } } } [aFetchedResultsController release]; [fetchRequest release]; [sortDescriptor release]; [sortDescriptors release]; return [orphans au

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