preparing a core data result set for a grouped uitableview - iphone

Question

i've got a NSMutableArray created from a data source object
NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
[self setAmountArray: mutableFetchResults];
every object in my mutable array has the two instance variables name and timeadded.
now i want to display all names in a uitableview grouped by the day they are added. for that i wrote the following method
-(NSMutableArray*)arrangeTransfersByDate:(NSMutableArray*)transferArray {
// Setting up objects for this method
NSDate *oldDate = [NSDate dateWithTimeIntervalSince1970:0.0f];
NSDateFormatter *dateComparisonFormatter = [[NSDateFormatter alloc] init];
[dateComparisonFormatter setDateFormat:#"yyyy-MM-dd"];
NSMutableArray *returnArray = [[NSMutableArray alloc] init];
for(transfers *transfer in transferArray) {
if( [[dateComparisonFormatter stringFromDate:[transfer timeadded]] isEqualToString:[dateComparisonFormatter stringFromDate:oldDate]] ) {
if([returnArray count] == 0) {
[returnArray addObject:[NSMutableArray arrayWithObject:transfer]];
} else {
[[returnArray objectAtIndex:[returnArray count]-1] addObject:transfer];
}
} else {
[returnArray addObject:[NSMutableArray arrayWithObject:transfer]];
oldDate = [transfer timeadded];
}
}
//[returnArray release];
[dateComparisonFormatter release];
return returnArray;
}
transferArray is my amountArray where my core data objects are stored.
so this works! but
is there a better way to do this? can you give me something like a "best practise" or simply have a look if there are some memory leaks?
thanks!
edit:
the right answer was NSFetchedResultController and its sectionNameKeyPath.
however i don't wanted to store my data twice a time.
so i created the following getter method in my NSManagedObject.
- (NSString *) pubDate {
[self willAccessValueForKey:#"pubDate"];
NSDateFormatter *dateComparisonFormatter = [[NSDateFormatter alloc] init];
[dateComparisonFormatter setDateFormat:#"dd.MM.YYYY"];
NSString *temp = [dateComparisonFormatter stringFromDate:[self pubTime]];
[dateComparisonFormatter release];
[self didAccessValueForKey:#"pubDate"];
return temp;
}
with this i can sort my tableviewcontroller by date using my FetchedResultController and my pubTime which is a timestamp.
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:[self managedObjectContext]
sectionNameKeyPath:#"pubDate"
cacheName:#"transfersRoot"];
thanks to all

Answer 1

Generally when you want to display the results of a Core Data fetch in a UITableView, you use an NSFetchedResultsController. You can choose the attribute by which you want to group your results by specifying a sectionNameKeyPath during initialization.
That said, provided your method works then really it's up to you whether you want to change your code around or not.
But please make sure you [returnArray autorelease] before you return it. It's a generally accepted Objective-C practice that any method without "alloc", "new", or "copy" in the name will return an autoreleased object.