如何使用Objective-C SDK使用Gmail API设置要读取/读取的邮件？

我编写了以下函数来通过标记未读来修改消息:

- (void)modifyMessageWithId:(NSString *)gmailMessageId
{
    __block GTLQueryGmail *query;
    query = [GTLQueryGmail queryForUsersMessagesModify];
    query.identifier = gmailMessageId;
    query.addLabelIds = @[@"UNREAD"];

    [self.gmailService executeQuery:query completionHandler:^(GTLServiceTicket *ticket, GTLGmailMessage *result, NSError *error) {
        // Check result here
    }];
}

然后我检查了结果,并且有一个错误说id(我认为这意味着query.identifier我设置)是一个未知的字段名称.我也尝试设置,query.messageId并得到一个类似的错误:

(lldb) po error

Error Domain=com.google.GTLJSONRPCErrorDomain Code=400 "The operation couldn’t be completed. (Unknown field name: id)" UserInfo=0xdd37e70 {error=Unknown field name: id, GTLStructuredError=GTLErrorObject 0xdd37cd0: {message:"Unknown field name: id" code:400 data:[1]}, NSLocalizedFailureReason=(Unknown field name: id)}

任何想法如何做到这一点？