Coredata and NSOrderedSet - how is the order of the set defined?

Question

I had a look through the existing documentation and couldn't find anything that confirms the behaviour I am seeing.

Starting on iOS 5, CoreData relationships can be ordered and in this case the returned object is a NSOrderedSet.

Can anyone confirm that the order of the objects in the set matches the order in which they have been created?

Cheers, Rog

Look out for this bug on NSOrderedSet - you need to override in order to make removals work: http://stackoverflow.com/a/7922993/1046685 — Damien Del Russo, Feb 29 '12 at 15:44

score 2 · Answer 1 · answered Feb 29 '12 at 10:58

If you don't sort the order yourself using sortedArrayUsingComparator: then I believe the objects are sorted in the order in which they are added.

You can also manual set the order with with – insertObject:atIndex: .

https://developer.apple.com/library/mac/#documentation/Foundation/Reference/NSMutableOrderedSet_Class/Reference/Reference.html#//apple_ref/occ/cl/NSMutableOrderedSet

score 1 · Answer 2 · answered Feb 06 '13 at 07:57

You should create a NSMutabledOrderedSet with data from your old NSOrderedSet, make your changes and move your data back again:

NSMutableOrderedSet *orderedSet = [[NSMutableOrderedSet alloc] initWithSet:[self.myOrderedSet set]];
[orderedSet insertObject:newObject atIndex:index];
self.myOrderedSet = orderedSet;

Coredata and NSOrderedSet - how is the order of the set defined?

2 Answers2