NSFileManager

//返回一个字符串数组(子路径), 并且不包含文件夹

[[NSFileManager defaultManager] contentsOfDirectoryAtPath:folderPath error:&error];

//返回一个字符串数组(子路径), 并且包含文件和文件夹

NSArray *subpaths = [[NSFileManager defaultManager] subpathsAtPath:folderPath];

        NSArray *subpaths2 = [[NSFileManager defaultManager] subpathsOfDirectoryAtPath:folderPath error:nil];