public static void StartPublishing(string meetingID, OnMessagePublished MessagePublishedHandler)
        {
            state = State.Publishing;
            //Clear all
            StopAll();
            currentMessage = meetingID;

            //Start NFC
            CrossNFC.Current.StartListening();
            CrossNFC.Current.StartPublishing();

            //Handlers
            tagDiscovered = SendData;
            CrossNFC.Current.OnTagDiscovered += tagDiscovered;

            OnMessagePublishedHandler = MessagePublishedHandler;

            messagePublished = MessagePublished;
            CrossNFC.Current.OnMessagePublished += messagePublished;
        }
        public static void StopAll()
        {
            try
            {
                CrossNFC.Current.OnMessageReceived -= messageReceived;
                messageReceived = null;

                CrossNFC.Current.OnMessagePublished -= messagePublished;
                messagePublished = null;

                CrossNFC.Current.OnTagDiscovered -= tagDiscovered;
                tagDiscovered = null;

                CrossNFC.Current.StopListening();
                CrossNFC.Current.StopPublishing();

                IsListening = false;
            }
            catch (Exception ex)
            {
            }
        }