- (void)tableView:(UITableView *)aTableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle 
      forRowAtIndexPath:(NSIndexPath *)indexPath {
  if (editingStyle == UITableViewCellEditingStyleDelete) {
    NSDictionary *section = [data objectAtIndex:indexPath.section];
    if (section) {
      NSMutableArray *content = [section valueForKey:@"content"];
      if (content && indexPath.row < [content count]) {
        [content removeObjectAtIndex:indexPath.row];
      }
    }
    [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
  } 
 else if (editingStyle == UITableViewCellEditingStyleInsert) {
    NSDictionary *section = [data objectAtIndex:indexPath.section];
    if (section) {
      // Make a local reference to the editing view controller.
      EditingViewController *controller = self.editingViewController;
      NSMutableArray *content = [section valueForKey:@"content"];
      // A "nil" editingItem indicates the editor should create a new item.
      controller.editingItem = nil;
      // The group to which the new item should be added.
      controller.editingContent = content;
      controller.sectionName = [section valueForKey:@"name"];
      controller.editingTypes = [section valueForKey:@"types"];
      [self.navigationController pushViewController:controller animated:YES];
    }
  }
}