// 缓存主目录
#define HSCachesDirectory [[NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"HSCache"]
// 保存文件名
#define HSFileName(url) [[url componentsSeparatedByString:@"/"] lastObject]
// 文件的存放路径（caches）
#define HSFileFullpath(url) [HSCachesDirectory stringByAppendingPathComponent:HSFileName(url)]
// 文件的已下载长度
#define HSDownloadLength(url) [[[NSFileManager defaultManager] attributesOfItemAtPath:HSFileFullpath(url) error:nil][NSFileSize] integerValue]
