NSFileManager
//判断某个路径是否是文件夹
BOOL isDirectory;
[[NSFileManagerdefaultManager] fileExistsAtPath:filePath isDirectory:&isDirectory];
//取得路径里包含的文件
NSArray *documentsDirectoryContents = [[NSFileManagerdefaultManager] contentsOfDirectoryAtPath:documentsDirectoryPath error:NULL];
//得到某个路径文件的参数
NSString *fileURLString = [self.docInteractionController.URL path];
NSDictionary *fileAttributes = [[NSFileManagerdefaultManager] attributesOfItemAtPath:fileURLString error:&error];
NSInteger fileSize = [[fileAttributes objectForKey:NSFileSize] intValue];
