I'm developing for iPhone iOS 4.0 and I have a list of birthday objects (date + name) stored using Core Data. I want to use the NSFetchedResultsController to retrieve this list sorted by the next birthdate date of each birthday object. For that I need to define my own logic for the sort descriptor.
I tried using:
[NSSortDescriptor sortDescriptorWithKey:@"birthdayDate"
ascending:YES
selector:@selector(compareNextBirthday:)];
Where compareNextBirthday:
is defined in a category I created on a NSDate class.
But when I try to fetch the data I get the following error: "unsupported NSSortDescriptor selector: compareNextBirthday:"
I spent hours trying to figure this out without luck... does Core Data support this kind of custom sorting at all? Do I really need to do an in-memory sort?