private async void CheckIn(int roomId)
        {
            if (string.IsNullOrWhiteSpace(FirstName) || string.IsNullOrWhiteSpace(LastName) || SelectedRoom == null)
            {
                MessageDialog dialog = new MessageDialog("You must enter first and last name and select a room", "Error");
                await dialog.ShowAsync();
                return;
            }

            var sensor = new Sensor
            {
                FirstName = FirstName,
                LastName = LastName,
                SensorId = 5,
                SensorMac = "1"
            };

            var presence = new SensorPresence
            {
                RoomId = roomId,
                SensorId = sensor.SensorId,
                TimeStamp = DateTime.Now
            };

            await serverHubProxy.Invoke("RecordLocation", presence, sensor);
            navigationService.NavigateTo("checkedInList");
        }
        private void GetSensorLocation(Sensor sensor)
        {
            if (sensor == null)
            {
                MessageDialog msgBox = new MessageDialog("You must choose a sensor", "Error");
                msgBox.ShowAsync();
                return;
            }
            var result = serverHubProxy.Invoke<SensorPresence>("GetSensorPresence", sensor).Result;
            var room = serverHubProxy.Invoke<Room>("GetRoom", result.RoomId).Result;

            SensorLocation = string.Format($"{SelectedSensor.FullName} was in {room.Name} at {result.TimeStamp}");
        }
        private async void GetSensorsLocation(Sensor sensor)
        {
            try
            {
                var sensorPresence = await serverHubProxy.Invoke<SensorPresence>("GetSensorPresence", sensor);
                var room = await serverHubProxy.Invoke<Room>("GetRoom", sensorPresence.RoomId);

                SensorsLocation = $"{sensor.FullName} was in {room.Name} at {sensorPresence.TimeStamp}";
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Error", MessageBoxButton.OK, MessageBoxImage.Error);
            }
        }