Sample code for the simple #IoT Police lights demo using Windows 10 IoT Core and a Raspberry Pi 3 with a couple LEDs https://twitter.com/BuildIoTCore/status/756542703786229764

PiIoTPoliceMainpage.xaml.cs

/// License: Public Domain
/// Written by: Chris Pietschmann
/// http://pietschsoft.com
/// http://BuildAzure.com
/// http://BuildIoTCore.com
/// 
/// This is the code behind the simple "#IoT police lights" shown
/// in the video at the following URL:
/// https://twitter.com/BuildIoTCore/status/756542703786229764
/// 

using System;
using Windows.Devices.Gpio;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Media;

namespace PiIoTPolice
{
    public sealed partial class MainPage : Page
    {
        DispatcherTimer timer;

        GpioPin pin;
        GpioPinValue pinValue;

        GpioPin pin2;
        GpioPinValue pin2Value;

        Brush onBrush = new SolidColorBrush(Windows.UI.Color.FromArgb(0, 0, 0, 255));
        Brush offBrush = new SolidColorBrush(Windows.UI.Color.FromArgb(0, 0, 0, 0));

        const int LED_PIN = 5;
        const int LED_PIN2 = 4;

        public MainPage()
        {
            //this.InitializeComponent();

            timer = new DispatcherTimer();
            timer.Interval = TimeSpan.FromMilliseconds(100);
            timer.Tick += Timer_Tick;
            InitGPIO();
            if (pin != null)
            {
                timer.Start();
            }
        }

        private void Timer_Tick(object sender, object e)
        {
            if (pinValue == GpioPinValue.High)
            {
                pinValue = GpioPinValue.Low;
                pin.Write(pinValue);
                //LED.Background = onBrush;
            }
            else
            {
                pinValue = GpioPinValue.High;
                pin.Write(pinValue);
                //LED.Background = offBrush;
            }

            if (pin2Value == GpioPinValue.High)
            {
                pin2Value = GpioPinValue.Low;
                pin2.Write(pin2Value);
            }
            else
            {
                pin2Value = GpioPinValue.High;
                pin2.Write(pin2Value);
            }
        }

        private void InitGPIO()
        {
            var gpio = GpioController.GetDefault();

            // Show an error if there is no GPIO controller
            if (gpio == null)
            {
                pin = null;
                //GpioStatus.Text = "There is no GPIO controller on this device.";
                return;
            }

            pin = gpio.OpenPin(LED_PIN);
            pinValue = GpioPinValue.High;
            pin.Write(pinValue);
            pin.SetDriveMode(GpioPinDriveMode.Output);

            pin2 = gpio.OpenPin(LED_PIN2);
            pin2Value = GpioPinValue.Low;
            pin2.Write(pin2Value);
            pin2.SetDriveMode(GpioPinDriveMode.Output);

            //GpioStatus.Text = "GPIO pin initialized correctly.";

        }
    }
}