async void btnScan_Click()
{
var dropdown = ddDevices.GetComponent <Dropdown>();
ddOptions.Clear();
mDevices.Clear();
dropdown.ClearOptions();
var devices = engine.BeginListDevices();
foreach (var dev in await devices)
{
Dropdown.OptionData option = new Dropdown.OptionData(string.Format("{0} - {1}", dev.Name, dev.Address));
ddOptions.Add(option);
mDevices.Add(dev);
}
dropdown.AddOptions(ddOptions);
}