Exception thrown in NSOrderedSet generated accessors

Question

On my Lion app, I have this data model:

The relationship subitem

Answer 1

I just got the problem in Swift (Xcode 6.1.1).

The answer was DO NOT CODE ANY METHOD OR ADDITIONAL THINGS in your NSManagedObject subclasses. I think it is a compilator mistake. Very strange bug ..

Hope it helps ..

Answer 2

I'm quite sure it is finally fixed in iOS 10 beta 6!

Answer 3

If you are using mogenerator, then instead of

[parentObject add<Child>sObject:childObject];

simply use:

[[parent object <child>sSet] addObject:childObject];

Answer 4

I agree that there may be 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.

Answer 5

Yes, this is definitely a Core Data bug. I wrote up an ObjC-Runtime-based fix a while back, but at the time I figured it would be fixed soon. Anyway, no such luck, so I posted it up on GitHub as KCOrderedAccessorFix. Work around the problem on all your entities:

[managedObjectModel kc_generateOrderedSetAccessors];

One entity in particular:

[managedObjectModel kc_generateOrderedSetAccessorsForEntity:entity];

Or just for one relationship:

[managedObjectModel kc_generateOrderedSetAccessorsForRelationship:relationship];

Answer 6

The Apple docs To Many Relations says: you should access the proxy mutable set or ordered set using

NSMutableOrderedSet * set = [managedObject mutableOrderedSetValueForKey:@"toManyRelation"];

Modifying this set will add or remove relations to your managed object. Accessing the mutable ordered set using the accessor whether with [ ] or . notation is wrong and will fail.