ios 获取文件扩展名备忘

NSString *lastComponent = [cachePath lastPathComponent];  
NSString *pathLessFilename = [cachePath stringByDeletingLastPathComponent];  
NSString *originalPath = [pathLessFilename stringByAppendingPathComponent: lastComponent];

NSString *pathExtension = [[cachePath pathExtension] lowercaseString];

NSLog(@"%@", lastComponent);

NSLog(@"%@", pathLessFilename);

NSLog(@"%@", originalPath);

NSLog(@"%@", pathExtension);