public void SendChannel(string channel, AgoraRtmMessage message)
        {
            var rtmChannels = AgoraRtm.RtmKit.Channels;

            if (rtmChannels[channel] is AgoraRtmChannel rtmChannel)
            {
                var options = new AgoraRtmSendMessageOptions
                {
                    EnableOfflineMessaging = AgoraRtm.OneToOneMessageType == OneToOneMessageType.Offline
                };

                rtmChannel.SendMessage(message, options, (state) =>
                {
                    Console.Write($"send channel msg state: {state}");

                    var current = AgoraRtm.Current;
                    if (current == null)
                    {
                        return;
                    }

                    AppendMsg(current, message);
                });
            }
        }
        public void SendPeer(string peer, AgoraRtmMessage message)
        {
            var options = new AgoraRtmSendMessageOptions
            {
                EnableOfflineMessaging = AgoraRtm.OneToOneMessageType == OneToOneMessageType.Offline
            };

            AgoraRtm.RtmKit.SendMessage(message, peer, options, (state) =>
            {
                Console.WriteLine($"send peer msg state: ({state})");

                var current = AgoraRtm.Current;
                AppendMsg(current, message);
            });
        }