from operator import attrgetter
ut.sort(key = attrgetter('count'), reverse = True)
Попробуйте следующее:
NSString * path = @"/Users/Me/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z";
NSError * error = nil;
BOOL success = [[NSFileManager defaultManager] createDirectoryAtPath:path
withIntermediateDirectories:YES
attributes:nil
error:&error];
if (!success || error) {
NSLog(@"Error! %@", error);
} else {
NSLog(@"Success!");
}