Example of Bluetooth in Xamarin.Forms applications - http://julianocustodio.com/bluetooth

MainPageInitialize.cs

namespace DemoBluetooth
{
    public partial class MainPage
    {

        IAdapter adapter;
        IBluetoothLE bluetoothBLE;
        ObservableCollection<IDevice> list;
        IDevice device;

        public MainPage()
        {
            InitializeComponent();

            bluetoothBLE = CrossBluetoothLE.Current;
            adapter = CrossBluetoothLE.Current.Adapter;

            list = new ObservableCollection<IDevice>();
            DevicesList.ItemsSource = list;
            
        }
    }
}