SourceCheckerTask.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;
using Windows.ApplicationModel.Background;
using ButterflyCore;
using Windows.UI.Notifications;
using Windows.Data.Xml.Dom;

namespace Background_Tasks
{
    public sealed class SourceCheckerTask : IBackgroundTask
    {
        public async void Run(IBackgroundTaskInstance taskInstance)
        {
            //Use .GetDeferral to prevent race conditions where the task finishes before async code completes.
            var deferral = taskInstance.GetDeferral();

            var core = new Client();
            var localSettings = ApplicationData.Current.LocalSettings;

            //Query the YouTube API for the latest video
            var query = await core.GetYouTubeUploads(1);

            //Ensure it was successful and that it contains data
            if (query.Success && query.Data?.data?.items != null)
            {
                //Get id of last checked video from app's local settings
                var lastVideoId = localSettings.Values["LastVideoId"] as string;

                //Get the latest video from the query
                var latestVideo = query.Data.data.items.FirstOrDefault();

                //If lastVideoId and latestVideo.id do not match, the returned video is new
                if (lastVideoId?.ToLower() != latestVideo?.id?.ToLower())
                {
                    //Show notification
                    try
                    {
                        var xml = ToastNotificationManager.GetTemplateContent(ToastTemplateType.ToastImageAndText01);

                        //Set toast image
                        ((XmlElement)xml.GetElementsByTagName("image")[0]).SetAttribute("src", latestVideo.thumbnail.sqDefault);

                        //Set toast text
                        xml.GetElementsByTagName("text")[0].AppendChild(xml.CreateTextNode("Jesse Cox has uploaded a new video!"));

                        //Show toast
                        ToastNotificationManager.CreateToastNotifier().Show(new ToastNotification(xml));
                    }
                    catch (Exception e)
                    {
                        //Do nothing. No way to warn user
                    }

                    //Store new video's id
                    localSettings.Values["LastVideoId"] = latestVideo.id;
                }
            }

            //Complete the task after all async code is finished.
            deferral.Complete();
        }
    }
}