Core Data Problem - select group by/having max

Question

Say I have two Entities:

Each Message belongs to a single MessageThread. How do I get all the message threads and the corresponding last message on that thread? Normally, in SQL, I'd do it as:

select __ from message group by thread having timeStamp=max(timeStamp)

For one, I don't think Core Data allows the @max in its predicates. Any ideas?

Answer 1

This might be a bit old, but I had a similar problem recently. Here is my solution to the problem:

NSFetchRequest *request = [[NSFetchRequest alloc] initWithEntityName:@"Message"];
request.predicate = [NSPredicate predicateWithFormat:@"timeStamp = [email protected]"];
request.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"timeStamp" ascending:NO]];

I hope it helps...