A test of the execution time difference between Foundation and CoreFoundation for string tokenizing and counting.

TokenizerTest

///Using Foundation.
-(void)getWordsFromString:(NSString *)string withFrequency:(NSUInteger)frequency completion:(void(^)(NSArray *array))block {
    NSDate *date = [NSDate date];
    __block NSTimeInterval interval = 0.0;
    NSMutableDictionary *temp = [NSMutableDictionary dictionaryWithCapacity:1000];
    [string enumerateSubstringsInRange:NSMakeRange(0, string.length) options:NSStringEnumerationByWords usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
        if(!temp[substring]) {
            temp[substring] = @1;
        }
        else {
            NSNumber *counted = temp[substring];
            counted = @(counted.integerValue + 1);
            temp[substring] = counted;
        }
        if(enclosingRange.location + enclosingRange.length == string.length) {
            NSArray *sortedArray = [[temp.allValues sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
                return [obj1 compare:obj2] != NSOrderedDescending;
            }]subarrayWithRange:NSMakeRange(0, (frequency > temp.count) ? temp.count : frequency)];
            NSMutableArray *finalArray = [NSMutableArray arrayWithCapacity:frequency];
            for(NSNumber *num in sortedArray) {
                [finalArray addObjectsFromArray:[temp allKeysForObject:num]];
            }
            interval += [date timeIntervalSinceNow];
            NSLog(@"%f",ABS(interval));
            block(finalArray);
        }
    }];
}

///Using CoreFoundation
-(NSArray *)getWordsFromString:(NSString *)string withFrequency:(NSUInteger)frequency {
    NSDate *date = [NSDate date];
    __block NSTimeInterval interval = 0.0;
    CFStringRef s = (__bridge CFStringRef)(string);
    
    CFMutableDictionaryRef dictRef = CFDictionaryCreateMutable(kCFAllocatorDefault, 1000, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
    CFStringTokenizerRef tokenizer = CFStringTokenizerCreate(kCFAllocatorDefault, s, CFRangeMake(0, CFStringGetLength(s)), kCFStringTokenizerUnitWord, CFLocaleCopyCurrent());
    
    CFStringTokenizerTokenType tokenType = kCFStringTokenizerTokenNone;
    
    while(kCFStringTokenizerTokenNone != (tokenType = CFStringTokenizerAdvanceToNextToken(tokenizer))) {
        CFRange tokenRange = CFStringTokenizerGetCurrentTokenRange(tokenizer);
        CFStringRef tokenValue = CFStringCreateWithSubstring(kCFAllocatorDefault, s, tokenRange);
        if(CFDictionaryContainsKey(dictRef, tokenValue) == false) {
            NSUInteger one = 1;
            CFDictionaryAddValue(dictRef, tokenValue, CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &one));
        }
        else {
            CFNumberRef number = CFDictionaryGetValue(dictRef, tokenValue);
            NSUInteger increment;
            CFNumberGetValue(number, kCFNumberIntType, &increment);
            increment += 1;
            CFDictionarySetValue(dictRef, tokenValue, CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &increment));
        }
        CFRelease(tokenValue);
    }

    CFRelease(tokenizer);
    NSMutableDictionary *temp = (__bridge NSMutableDictionary *)(dictRef);

    NSArray *sortedArray = [[temp.allValues sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        return [obj1 compare:obj2] != NSOrderedDescending;
    }]subarrayWithRange:NSMakeRange(0, (frequency > temp.count) ? temp.count : frequency)];
    NSMutableArray *finalArray = [NSMutableArray new];
    for(NSNumber *num in sortedArray) {
        [finalArray addObjectsFromArray:[temp allKeysForObject:num]];
    }
    interval += [date timeIntervalSinceNow];
    NSLog(@"%f",ABS(interval));
    return finalArray;
}