ios - Core Data Child Ordered Set

Question

I have two entities (Order and Cart) in core data with a parent child relationship. The generated parent class has a property to access the child records.

@interface Order : NSManagedObject

@property(nonatomic, retain) NSOrderedSet *carts;

@end

Say, Cart has a field 'x', is it possible to tell core data framework to keep the carts collection above always ordered by x?

Answer 1

Not with an NSOrderedSet. If you have a logical sort for your children then you should not bother with a NSOrderedSet at all and just leave them as unordered. After that change you can use a NSSortDescriptor to sort the children into an NSArray.

That will yield better performance for you compared to a NSOrderedSet and will let you sort by x.

Ordered relationships are very expensive and should be avoided unless there is an absolute necessity.