DeviceArrivedEventHandler delegate

public delegate void DeviceArrivedEventHandler(
  ProximityDevice sender
)

Windows.Networking.Proximity.ProximityDevice proximityDevice;

private void InitializeProximityDevice()
{
    proximityDevice = Windows.Networking.Proximity.ProximityDevice.GetDefault();

    if (proximityDevice != null) {
        proximityDevice.DeviceArrived += ProximityDeviceArrived;
        proximityDevice.DeviceDeparted += ProximityDeviceDeparted;

        WriteMessageText("Proximity device initialized.\n");
    }
    else
    {
        WriteMessageText("Failed to initialized proximity device.\n");
    }
}

private void ProximityDeviceArrived(Windows.Networking.Proximity.ProximityDevice device)
{
    WriteMessageText("Proximate device arrived. id = " + device.DeviceId + "\n");
}

private void ProximityDeviceDeparted(Windows.Networking.Proximity.ProximityDevice device)
{
    WriteMessageText("Proximate device departed. id = " + device.DeviceId + "\n");
}

// Write a message to MessageBlock on the UI thread.
private Windows.UI.Core.CoreDispatcher messageDispatcher = Window.Current.CoreWindow.Dispatcher;

async private void WriteMessageText(string message, bool overwrite = false)
{
    await messageDispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal,
        () =>
        {
            if (overwrite)
                MessageBlock.Text = message;
            else
                MessageBlock.Text += message;
        });
}