Objective-C `chunk`

#import <Foundation/Foundation.h>

int main (int argc, char **argv)
{
    @autoreleasepool {
        const NSUInteger iterations = 10000000;
        const NSUInteger variation  = 10000000;

        NSMutableArray *original = [NSMutableArray arrayWithCapacity:iterations];
        for (NSUInteger i = 0; i < iterations; i++) {
            [original addObject:@(arc4random_uniform(variation))];
        }

        NSMutableArray *chunked = [NSMutableArray array];
        NSDate *start = [NSDate date];

#define ARRAY
#ifdef ARRAY
        NSArray *sorted = [original sortedArrayUsingSelector:@selector(compare:)];
        NSNumber *current = nil;
        for (NSNumber *number in sorted) {
            if (![number isEqual:current]) {
                [chunked addObject:[NSMutableArray arrayWithObject:number]];
                current = number;
            } else {
                [[chunked lastObject] addObject:number];
            }
        }
#else
        NSCountedSet *countedSet = [[NSCountedSet alloc] initWithArray:original];
        for (NSNumber *number in countedSet) {
            NSMutableArray *chunk = [NSMutableArray array];
            NSUInteger count = [set countForObject:number];
            for (NSUInteger i = 0; i < count; i++) {
                [chunk addObject:number];
            }

            [chunked addObject:chunk];
        }

        [chunked sortUsingComparator:^(NSArray *a1, NSArray *a2) {
            return [a1[0] compare:a2[0]];
        }];
#endif

        NSLog(@"Operation took %lf seconds.", [[NSDate date] timeIntervalSinceDate:start]);
    }

    return 0;
}