下载对象时，可以重写部分HTTP/HTTPS响应头信息。可重写的响应头信息见下表：

以下代码展示了如何重写响应头：

static OBSClient *client;NSString *endPoint = @"your-endpoint";// 认证用的ak和sk硬编码到代码中或者明文存储都有很大的安全风险，建议在配置文件或者环境变量中密文存放，使用时解密，确保安全；本示例以ak和sk保存在环境变量中为例，运行本示例前请先在本地环境中设置环境变量AccessKeyID和SecretAccessKey。// 您可以登录访问管理控制台获取访问密钥AK/SK，获取方式请参见https://support.huaweicloud.com/usermanual-ca/ca_01_0003.htmlchar* ak_env = getenv("AccessKeyID");char* sk_env = getenv("SecretAccessKey");NSString *AK = [NSString stringWithUTF8String:ak_env];NSString *SK = [NSString stringWithUTF8String:sk_env];    // 初始化身份验证OBSStaticCredentialProvider *credentialProvider = [[OBSStaticCredentialProvider alloc] initWithAccessKey:AK secretKey:SK];    //初始化服务配置OBSServiceConfiguration *conf = [[OBSServiceConfiguration alloc] initWithURLString:endPoint credentialProvider:credentialProvider];    // 初始化clientclient = [[OBSClient alloc] initWithConfiguration:conf];    // 流式下载OBSGetObjectToDataRequest *request = [[OBSGetObjectToDataRequest alloc]initWithBucketName:@"bucketname" objectKey:@"objectname"];    //重写ContentTyperequest.responseContentType = @"image/jpeg";        // 下载进度request.downloadProgressBlock = ^(int64_t bytesWritten, int64_t totalBytesWritten, int64_t totalBytesExpectedToWrite) {    NSLog(@"%0.1f%%",(float)(totalBytesWritten)*100/(float)totalBytesExpectedToWrite);};    // 下载的数据__block NSMutableData *objectData = [NSMutableData new];request.onReceiveDataBlock = ^(NSData *data) {    [objectData appendData:data];};    // 下载结果[client getObject:request completionHandler:^(OBSGetObjectResponse *response, NSError *error){    NSLog(@"%@",response);}] ;