Sorting NSFetchedResultsController by NULL NSDates
ios, nsfetchedresultscontroller, nssortdescriptor, objective-c, sorting
Solution
I ended up doing what they mentioned here: Using NSSortDescriptor to keep blank values down the list
I made a BOOL value that indicates whether or not the user has reminder set. So, I sort by presence of a reminder, and then by date.
NSSortDescriptor *sortByDate = [NSSortDescriptor sortDescriptorWithKey:@"reminderDate" ascending:YES];
NSSortDescriptor *sortByHasReminder = [NSSortDescriptor sortDescriptorWithKey:@"hasReminder" ascending:NO];
It works well. As a database enthusiast, I hate having unnecessary fields, but it's the best I can do with NSSFetchedResultsController.
Problem
I have a tableview that loops through an array of data. The data is a set of contacts that may have a reminder time attached to them. For example: - Jessica - John - Bill - Katrina (February 9th) - Brian (February 11th) Right now, it sorts the tableview via the core-data attribute `reminderDate` in ascending manner. It works semi-correctly. The only catch is I'd like for the items that have a `NULL` `reminderDate` to be thrown to the end of the `NSFetchedResultsController` instead of at the beginning. Ideally, it'd look like this: - Katrina (February 9th) - Brian (February 11th) - Jessica - John - Bill I can't use a comparative `NSSortDescriptor` as it's not supported by `NSFetchedResultsController`. Also, I'd rather not perform a sorting after I get results from the `NSFetchedResultsController` but rather before, when I make the query. Here is the current code I use: ``` NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"User"]; NSSortDescriptor *sortByDate = [NSSortDescriptor sortDescriptorWithKey:@"reminderDate" ascending:YES]; [fetchRequest setSortDescriptors:@[sortByDate]]; self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:nil cacheName:nil]; ``` I believe I should be adding another sortDescriptor, but haven't gotten anything to work properly.