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); }