Re: CoreData and mutableArrayValueForKey:
Re: CoreData and mutableArrayValueForKey:
- Subject: Re: CoreData and mutableArrayValueForKey:
- From: Quincey Morris <email@hidden>
- Date: Sat, 30 Aug 2008 19:24:56 -0700
On Aug 30, 2008, at 14:23, Alex Duzik wrote:
I'm writing an app where one Core Data entity -- Folder -- has
(conceptually) a to-many relationship with another object -- Item.
But I want to keep those items in a particular order, so I have a
third entity, OrderedItem, which keeps a reference to the folder
along with a reference to the item and also adds an order attribute
to track the item's position in the folder.
This is rather cumbersome to maintain, so I've implemented the key-
value coding methods for a to-many relationship:
- (NSUInteger) countOfItems
- (Item *)objectInItemsAtIndex:(NSUInteger)index;
- (void)insertObject:(Item *)item inObjectsAtIndex:(NSUInteger)index;
- (void)removeObjectFromItemsAtIndex:(NSUInteger)index;
The 3rd method should be insertObject:inItemsAtIndex:, so your "items"
property isn't fully KVC compliant.
You might want to consider, as an alternative, putting the order
attribute directly in the Item entity, and get a sorted array using a
fetch request.
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