In my app, I have a task list (no, it's not just another todo app), and I display the tasks in a UITableView using an NSFetchedResultsController. Here is the relevant initialisation code:

NSSortDescriptor *dueDateSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"due" YES];
NSSortDescriptor *completionSortDescriptor = [NSSortDescriptor sortDescriptorWithKey:@"completed" ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObjects:completionSortDescriptor, dueDateSortDescriptor, nil]];

_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"completed" cacheName:nil];

What this does is sorts the tasks such that I have an incomplete tasks section at the top, sorting with the tasks due first on top, and tasks due later further down. This all works.

However, this means that the second section, the one with the completed tasks, also sorts this way, so the earliest due tasks are on top. What I want to do is change it so the second section sorts the other way around (in descending order), but the first section stays sorted in ascending order. Is this even possible? How would I go about this?

Why I want to do this: The way it currently works, the tasks at the top of the second section (and therefore the most visible) are the ones that were completed ages ago. It is more likely that the user would want to see the tasks that are more recently completed (and uncheck one if it was accidentally checked), and presumably the tasks with a more recent due date were more recently completed. I am happy to add a separate completion date field to the Core Data task object if necessary (This isn't a shipping application yet, so I can change the data format however I like).