环信iOS,SDK3.2.2如何获取两个人的聊天记录,目前只能获取一个人的....

/*!
 *  \~chinese
 *  从数据库获取指定数量的消息，取到的消息按时间排序，并且不包含参考的消息，如果参考消息的ID为空，则从最新消息取
 *
 *  @param aMessageId       参考消息的ID
 *  @param count            获取的条数
 *  @param aDirection       消息搜索方向
 *  @param aCompletionBlock 完成的回调
 *
 *  \~english
 *  Load messages from a specified message, returning messages are sorted by receiving timestamp. If the aMessageId is nil, return the latest received messages.
 *
 *  @param aMessageId       Reference message's ID
 *  @param aCount           Count of messages to load
 *  @param aDirection       Message search direction
 *  @param aCompletionBlock The callback block of completion
 *
 */
- (void)loadMessagesStartFromId:(NSString *)aMessageId
                          count:(int)aCount
                searchDirection:(EMMessageSearchDirection)aDirection
                     completion:(void (^)(NSArray *aMessages, EMError *aError))aCompletionBlock;