res

        public MainPage()
        {
            this.InitializeComponent();
            lbPerson.ItemsSource = p;
            Application.Current.Suspending += new SuspendingEventHandler(App_Suspending);
            Application.Current.Resuming += new EventHandler<Object>(App_Resuming);

        }
        private async void App_Suspending(Object sender, Windows.ApplicationModel.SuspendingEventArgs e)
        {
            var folder = Windows.Storage.ApplicationData.Current.RoamingFolder;
            var localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;
            localSettings.Values["Name"] = tbName.Text;
            localSettings.Values["Surname"] = tbSurname.Text;
            var file = await folder.CreateFileAsync("collection.json", CreationCollisionOption.ReplaceExisting);
            using (var stream = await file.OpenStreamForWriteAsync())
            using (var writer = new StreamWriter(stream, Encoding.UTF8))
            {
                string json = JsonConvert.SerializeObject(p);
                await writer.WriteAsync(json);
            }
        }
        private async void App_Resuming(Object sender, Object e)
        {
            var localSettings = Windows.Storage.ApplicationData.Current.LocalSettings;
            tbName.Text = localSettings.Values["Name"].ToString();
            tbSurname.Text = localSettings.Values["Surname"].ToString();
            var folder = ApplicationData.Current.RoamingFolder;
            var file = await folder.GetFileAsync("collection.json");
            using (var stream = await file.OpenStreamForReadAsync())
            using (var reader = new StreamReader(stream, Encoding.UTF8))
            {
                string json = await reader.ReadToEndAsync();
                var collection = JsonConvert.DeserializeObject<ObservableCollection<Persons>>(json);
                p = collection;
            }
        }