Exception thrown in NSOrderedSet generated accessors

Question

On my Lion app, I have this data model:

The relationship subitem

Answer 1

I agree that there maybe a bug here. I've modified the implementation of the add object >setter to append correctly to a NSMutableOrderedSet.

- (void)addSubitemsObject:(SubItem *)value {
     NSMutableOrderedSet* tempSet = [NSMutableOrderedSet orderedSetWithOrderedSet:self.subitems];
     [tempSet addObject:value];
     self.subitems = tempSet;
}

Reassigning the set to self.subitems will ensure that the Will/DidChangeValue notifications >are sent.

Leelll, are you sure that after such custom setup of NSMutableOrderedSet values stored in that set will be saved to the database correctly by CoreData? I didn't check that, but it looks like CoreData knows nothing about NSOrderedSet and expects NSSet as to-many relationship container.