ViewMqtt.cs

public class ViewMqtt : ContentPage{

	void Btn_Clicked (object sender, EventArgs e)
		{
			var client = DependencyService.Get<IFMqttClient> ();
			client.Connect ("borkerLink");
			client.Publish ("topicoQueRecebeMensagem", Encoding.UTF8.GetBytes ("mensagemEnviada"));
			var topics = new string[] { 
				"Topico1 a ser assinado (subscribe)"
			};
			foreach (var item in topics) {
				Xamarin.Forms.MessagingCenter.Subscribe<MqqtReceived> (this, item, (t) => myByteAction (t));
			}
			client.Subscribe (topics);
		}
		public void myByteAction (MqqtReceived ReceivedObject)
		{
			var msg = Encoding.UTF8.GetString (ReceivedObject.Message, 0, ReceivedObject.Message.Length);
			Device.BeginInvokeOnMainThread (() => {
				switch ("Topico1 a ser assinado (subscribe)") {
				case Constants.GeneralTopic:
					//JsonConvert to Object
					var surf = Newtonsoft.Json.JsonConvert.DeserializeObject<Surfboard> (msg);
					System.Diagnostics.Debug.WriteLine (surf);
					break;
				default:
					System.Diagnostics.Debug.WriteLine ("Mensagem recebida da IoT: " + msg);	
					break;
				}
			});
		}
}