V2TimValueCallback<V2TimMsgCreateInfoResult> createCustomMessageRes =
      await TencentImSDKPlugin.v2TIMManager
          .getMessageManager()
          .createCustomMessage(
            data: '正在输入中',
          );
// 发送消息时，需要把needReadReceipt设置为true
  TencentImSDKPlugin.v2TIMManager.getMessageManager().sendMessage(id: createCustomMessageRes.data.id, receiver: "", groupID: "groupID",onlineUserOnly: true,needReadReceipt: true);

V2TimCallback sendMessageReadReceipts = await TencentImSDKPlugin.v2TIMManager.getMessageManager().sendMessageReadReceipts(messageIDList: ['msgids']);
  if(sendMessageReadReceipts.code == 0){
    // 成功
  }else{
    // 失败
  }

onRecvMessageReadReceipts: (List<V2TimMessageReceipt> receiptList) {
      receiptList.forEach((element) { 
        element.groupID;  // 群id
        element.msgID; // 已读回执消息 ID
        element.readCount;// 群消息最新已读数
        element.unreadCount;// 群消息最新未读数
        element.userID; //  C2C 消息对方 ID
      });
},

V2TimValueCallback<List<V2TimMessageReceipt>> getMessageReadReceipts = await  TencentImSDKPlugin.v2TIMManager.getMessageManager().getMessageReadReceipts(messageIDList: []);
  if(getMessageReadReceipts.code == 0){
    getMessageReadReceipts.data.forEach((element) {
      // 解析群消息已读回执
      element.groupID;
      element.msgID;
      element.readCount;
      element.timestamp;
      element.unreadCount;
      element.userID;
    });
  }

V2TimValueCallback<V2TimGroupMessageReadMemberList> getGroupMessageReadMemberList = await  TencentImSDKPlugin.v2TIMManager.getMessageManager().getGroupMessageReadMemberList(messageID: "", filter: GetGroupMessageReadMemberListFilter.V2TIM_GROUP_MESSAGE_READ_MEMBERS_FILTER_READ,);

 if(getGroupMessageReadMemberList.code == 0){
   // 获取群消息已读未读群成员列表
   getGroupMessageReadMemberList.data.isFinished;
   getGroupMessageReadMemberList.data.memberInfoList;
   getGroupMessageReadMemberList.data.nextSeq;
 }