public async Task <bool> AddItem(string id, string url)
        {
            if (UrlContentCheckerList.Where(m => { if (m.id == id)
                                                   {
                                                       return(true);
                                                   }
                                                   else
                                                   {
                                                       return(false);
                                                   } }).Count() > 0)
            {
                return(false);
            }
            Uri uri;

            try
            {
                uri = new Uri(url);
            }
            catch
            {
                return(false);
            }
            var newOne = new UrlContentChangeChecker(id, uri);

            if (!await newOne.CheckExistance())
            {
                await newOne.CheckNow();
            }
            UrlContentCheckerList.Insert(0, newOne);

            return(true);
        }
        public async Task Init()
        {
            UrlContentCheckerList.Clear();
            var local   = ApplicationData.Current.LocalFolder;
            var Folders = await local.GetFoldersAsync();

            var Tasks = new List <Task <bool> >();

            foreach (var m in Folders)
            {
                var uccc = new UrlContentChangeChecker(m.Name);
                Tasks.Add(uccc.CheckExistance());
                UrlContentCheckerList.Add(uccc);
            }
            foreach (var m in Tasks)
            {
                await m;
            }
        }