Advanced Sorting of NSArray with Functions

NSInteger cardSortAsc(id card1, id card2, void *keyForSorting)
{
    int v1 = [[card1 objectForKey:(NSString *)keyForSorting] intValue];
    int v2 = [[card2 objectForKey:(NSString *)keyForSorting] intValue];
    if (v1  v2)
        return NSOrderedDescending;
    else
        return NSOrderedSame;
}
 
NSInteger cardSortDesc(id card1, id card2, void *keyForSorting)
{
    int v1 = [[card1 objectForKey:(NSString *)keyForSorting] intValue];
    int v2 = [[card2 objectForKey:(NSString *)keyForSorting] intValue];
    if (v1 > v2)
        return NSOrderedAscending;
    else if (v1 < v2)
        return NSOrderedDescending;
    else
        return NSOrderedSame;
}
 
- (NSArray *) cardsIn:(NSDictionary *)cards sortedBy:(NSString *)keyForSorting ascending:(BOOL)ascending
{
	// first transfer the dictionary into an array, moving the key into a sub of each card dict
	NSMutableArray *unsortedCards = [NSMutableArray array];
	for (NSString *oneCardKey in cards)
	{
		NSMutableDictionary *tmpCard = [[cards objectForKey:oneCardKey] mutableCopy];
		[tmpCard setObject:oneCardKey forKey:@"index"];  // add the card key as field "index"
		[unsortedCards addObject:tmpCard];
		[tmpCard release];
	}
 
	// sort into a new array
	NSArray *sortedCards;
 
	if (ascending)
	{
		sortedCards = [unsortedCards sortedArrayUsingFunction:cardSortAsc context:keyForSorting];
	}
	else
	{
		sortedCards = [unsortedCards sortedArrayUsingFunction:cardSortDesc context:keyForSorting];
	}
 
	// now extract the indexes into their own array
	NSMutableArray *tmpArray = [NSMutableArray array];
 
	/* -- variant returning all cards
	for (NSDictionary *oneCard in sortedCards)
	{
		[tmpArray addObject:[oneCard objectForKey:@"index"]];
	}
	 */
 
	/* -- variant returning only first 10 cards */
	for (int i=0;i<10;i++)
	{
		NSDictionary *oneCard = [sortedCards objectAtIndex:i];
		[tmpArray addObject:[oneCard objectForKey:@"index"]];
 
	}
 
	NSArray *retArray = [NSArray arrayWithArray:tmpArray]; // make immutable, autoreleased
 
	return retArray;
}
 
- (void)applicationDidFinishLaunching:(UIApplication *)application {
 
    // Override point for customization after app launch
    [window addSubview:viewController.view];
    [window makeKeyAndVisible];
 
	// TEST FOLLOWING
 
	// load dictionary of cards
	NSBundle *thisBundle = [NSBundle bundleForClass:[self class]]; // alternate method to get bundle
	NSString *cardsPath = [thisBundle pathForResource:@"cards" ofType:@"plist"];
	NSDictionary *cards = [NSDictionary dictionaryWithContentsOfFile:cardsPath];
 
	NSArray *keysSortedByCapacity = [self cardsIn:cards sortedBy:@"capacity" ascending:NO];
 
	// test output
	for (NSString *cardKey in keysSortedByCapacity)
	{
		NSLog([[cards objectForKey:cardKey] description]);
	}
}

NSInteger letterSortDesc(id letter1, id letter2, void *dummy)
{
    int v1 = [[letter1 objectForKey:@"Count"] intValue];
    int v2 = [[letter2 objectForKey:@"Count"] intValue];
    if (v1 > v2)
        return NSOrderedAscending;
    else if (v1 < v2)
        return NSOrderedDescending;
    else
        return NSOrderedSame;
}
 
- (NSArray *) lettersSortedByUsage
{
	NSMutableDictionary *letterCounts = [NSMutableDictionary dictionary]; // autoreleased
	NSMutableArray *letterCountsArray = [NSMutableArray array];
 
	// all sentences
	for (NSDictionary *oneSentenceDict in sentences)
	{
		NSString *oneSentence = [oneSentenceDict objectForKey:@"String"];
 
		// go through all characters
		for (int i=0; i<[oneSentence length];i++)
		{
			NSString *letter = [[oneSentence substringWithRange:NSMakeRange(i, 1)] uppercaseString];
 
			NSRange r =  ([letter rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]]);
 
			if (r.location==0) // letter is alpha
			{
				NSMutableDictionary *letterDict = [letterCounts objectForKey:letter];
 
				if (!letterDict)
				{
					// did not encounter letter before
					letterDict = [NSMutableDictionary dictionary];
					[letterDict setObject:[NSNumber numberWithInt:1] forKey:@"Count"];
					[letterDict setObject:letter forKey:@"Letter"];
					[letterCounts setObject:letterDict forKey:letter];
					[letterCountsArray addObject:letterDict];
				}
				else
				{
					// add 1 to existing letter
					int newInt = [[letterDict objectForKey:@"Count"] intValue]+1;
					NSNumber *newNum = [NSNumber numberWithInt:newInt];
 
					[letterDict setObject:newNum forKey:@"Count"];
				}
			}
		}
	}
 
	// now we need to sort the array by descending count
	NSArray *sortedLetters = [letterCountsArray sortedArrayUsingFunction:letterSortDesc context:nil];
 
	return [NSArray arrayWithArray:sortedLetters]; // immutable, autoreleased
}