iphone - A NSFetchedResultsController with date as sectionNameKeyPath

Question

I develop an application which uses Core Data. In one UITableView, I want to display a list of my entities, sorted by the saved date of the objects. When I do this:

fetchedResultsController = [[NSFetchedResultsController alloc]
                            initWithFetchRequest:fetchRequest
                            managedObjectContext:managedObjectContext
                              sectionNameKeyPath:@"date"
                                       cacheName:nil];

I get for each object a new section because this code groups the dates according to the seconds, too. But I want a list of the objects, grouped by date, but only according to the day, month and year. Is it possible and how?

Thank you very much for your help!! ;)

Answer 1

This should do the trick for you:

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
  NSString *rawDateStr = [[[self.fetchedResultsController sections] objectAtIndex:section] name];
  // Convert rawDateStr string to NSDate...
  NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];
  [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss ZZ"];
  NSDate *date = [formatter dateFromString:rawDateStr];

  // Convert NSDate to format we want...
  [formatter setDateFormat:@"d MMMM yyyy"];
  NSString *formattedDateStr = [formatter stringFromDate:date];
  return formattedDateStr;  
}

[EDIT]

Jus saw your comment and for what you are trying to achieve, you could create a transient NSDate attribute (non persistent) that is formatted in a similar way to the above code (i.e. without H:mm:ss ZZZZ) and use that attribute as your sectionNameKeyPath value.

So in a nutshell for a foo object, with fooDate and fooDateTransient attributes, you would:

1. Get your foo.fooDate attribute

2. Transform it using the code above (or similar) and assign the NSDate result to foo.fooDateTransient

3. Use fooDateTransient as your sectionNameKeyPath when creating the fetchedResultsController object.

PS: I haven't tested this myself but should be worth a shot!

Good luck, Rog