how to find the folder size in iphone sdk?

//.h file

unsigned long long int fileSize;

- (unsigned long long int)folderSize:(NSString *)folderPath;

-(void)checkTotalSize;


// .m file

NSString *folderPath = @"/Users/Desktop/myFolder";
    [self folderSize:folderPath];


- (unsigned long long int)folderSize:(NSString *)folderPath {
   
    NSArray *filesArray = [[NSFileManager defaultManager] subpathsOfDirectoryAtPath:folderPath error:nil];
    NSEnumerator *filesEnumerator = [filesArray objectEnumerator];
    NSString *fileNames;
    //unsigned long long int fileSize = 0;
    fileSize = 0;
   
    while (fileNames = [filesEnumerator nextObject]) {
        NSDictionary *fileDictionary = [[NSFileManager defaultManager] attributesOfItemAtPath:[folderPath stringByAppendingPathComponent:fileNames] error:nil];
        fileSize += [fileDictionary fileSize];
    }
    NSLog(@"filesize==%llu",fileSize);
    [self checkTotalSize];
    return fileSize;
}

-(void)checkTotalSize {
   
    fileSize = fileSize ;//   + totalLength;     // totallength is current file size
   
    NSLog(@"totsize==%llu",fileSize);
   
    if (fileSize >= 1000000000) {
        [self.urlConnection cancel];
        receivedData = nil;
     }
}