无法更新 AsyncCallback 方法中的 date 属性

问：

无法更新 Date 属性 更新 Date 属性

这是我面临的问题的代码片段

public DateTime LastReceivedImplicitMessage { get; set;

var asyncResult = udpClientReceive.BeginReceive（ new AsyncCallback（ReceiveCallbackClass1）， s）;

private void ReceiveCallbackClass1 （IAsyncResult ar） { 尝试 {

            UdpClient u = (UdpClient)((UdpState)(ar.AsyncState)).u;
            if (udpClientReceiveClosed)
                return;

            u.BeginReceive(new AsyncCallback(ReceiveCallbackClass1), (UdpState)(ar.AsyncState));
            System.Net.IPEndPoint e = (System.Net.IPEndPoint)((UdpState)(ar.AsyncState)).e;


            Byte[] receiveBytes = u.EndReceive(ar, ref e);

            // EndReceive worked and we have received data and remote endpoint

            if (receiveBytes.Length > 20)
            {
                //Get the connection ID
                uint connectionID = (uint)(receiveBytes[6] | receiveBytes[7] << 8 | receiveBytes[8] << 16 | receiveBytes[9] << 24);


                if (connectionID == connectionID_T_O)
                {

                    ushort headerOffset = 0;
                    if (T_O_RealTimeFormat == RealTimeFormat.Header32Bit)
                        headerOffset = 4;
                    if (T_O_RealTimeFormat == RealTimeFormat.Heartbeat)
                        headerOffset = 0;
                    for (int i = 0; i < receiveBytes.Length - 20 - headerOffset; i++)
                    {
                        T_O_IOData[i] = receiveBytes[20 + i + headerOffset];
                    }
                    
                    //Console.WriteLine(T_O_IOData[0]);


                }
            }
            
            LastReceivedImplicitMessage = DateTime.Now;

        }
        catch (Exception ex) { }
    }

“LastReceivedImplicitMessage”未使用 datetime.now 更新