//获得指定文件距离上次修改时间是否达到了指定值(秒)timeout    +(BOOL)isTimeout:(NSString *)path time:(NSTimeInterval)timeout    {        //获得当前时间        NSTimeInterval now = [[NSDate date] timeIntervalSince1970];                NSDictionary *dict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];        // 取得了文件上次修改的时间        NSDate *d = [dict objectForKey:NSFileModificationDate];        if (now-[d timeIntervalSince1970]>timeout) {            return YES;        }        return NO;    }    //计算文件夹下文件的总大小    +(float)fileSizeForDir:(NSString*)path    {        NSFileManager *fileManager = [NSFileManager defaultManager];                //记录总值        unsigned long long totalSize =0;        //获得指定路径path的所有内容(文件和文件夹)        NSArray* array = [fileManager contentsOfDirectoryAtPath:path error:nil];        for(int i = 0; i<[array count]; i++)        {            //拼接全路径            NSString *fullPath = [path stringByAppendingPathComponent:[array objectAtIndex:i]];            BOOL isDir;                        //如果指定路径存在并且不是文件夹            //NSLog(@"fullPath:%@",fullPath);            //先判断是否存在，再判断是文件夹还是文件            if ([fileManager fileExistsAtPath:fullPath isDirectory:&isDir] && !isDir)            {                //获得文件属性                NSDictionary *fileAttributeDic=[fileManager attributesOfItemAtPath:fullPath error:nil];                totalSize+=[[fileAttributeDic objectForKey:NSFileSize] unsignedLongLongValue];            }            else            {                //如果是文件夹，递归                totalSize+=[self fileSizeForDir:fullPath];            }        }        return totalSize;    }