title: Add empty section to NSFetchedResultsController
body: <p>I am making a view just like the iPhone Calendar ListView. I am using core data and getting appointments and grouping them by date.</p>
  
  <p>However just like in the iPhone listview I need to add a blank section for today even if there are no appointments. I cannot figure out how to do this for a section with no appointments since I am doing the sorting before I create the grouping.</p>
  
  <p>How would I add an empty section to the <code>NSFetchedResultsController</code> and have it resorted so that today's date is in the correct spot and not at the end of the list?</p>
  
  <pre><code>- (NSFetchedResultsController *)fetchedResultsController {
  
      /*
       Set up the fetched results controller.
       */
      // Create the fetch request for the entity.
      NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
      // Edit the entity name as appropriate.
      NSEntityDescription *entity = [NSEntityDescription entityForName:@"Appointments" inManagedObjectContext:[[CoreDataHelper sharedInstance] managedObjectContext]];
      [fetchRequest setEntity:entity];
      //[fetchRequest setIncludesPendingChanges:YES];
  
      // Set the batch size to a suitable number.
      //[fetchRequest setFetchBatchSize:20];
  
      // Sort using the date / then time property.
      NSSortDescriptor *sortDescriptorDate = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];
      NSSortDescriptor *sortDescriptorTime = [[NSSortDescriptor alloc] initWithKey:@"start_time" ascending:YES selector:@selector(localizedStandardCompare:)];
      NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptorDate, sortDescriptorTime, nil];
  
  
      [fetchRequest setSortDescriptors:sortDescriptors];
  
      // Use the sectionIdentifier property to group into sections.
      NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:[[CoreDataHelper sharedInstance] managedObjectContext] sectionNameKeyPath:@"date" cacheName:nil];
      aFetchedResultsController.delegate = self;
      self.fetchedResultsController = aFetchedResultsController;
      return fetchedResultsController;
  } 
  </code></pre>