Как я могу динамически загружать данные, которые хранятся в моем изолированном хранилище данных

Question

Я хочу добавить данные, которые хранятся в моем изолированном хранилище данных, когда я достигну последнего индекса списка, но я не знаю, как я это делаю, я нашел одно решение для этого, т.е. .. http://blogs.microsoft.co.il/blogs/shair/archive/2011/04/06/wp7-how-to-extend-listbox-when-reaching-last-item.aspx Я преобразовал его в мое требование, и это код, который я делаю, но проблема в том, когда я добавляю новый элемент, который хранится в моем хранилище данных .. Фактически здесь я добавляю тот же элемент, который находится в моем хранилище данных, но элемент не добавляется.... соответственно, когда я достигну последнего индекса ...

     ObservableCollection<Discrip> list = new ObservableCollection<Discrip>();
    static ObservableCollection<Discrip> lst = new ObservableCollection<Discrip>();
    ScrollViewer scrollViewer;
    public MainPage()
    {
        InitializeComponent();
        ListBoxDemo.Loaded += new RoutedEventHandler(ListBoxDemo_Loaded);
        AddDummyItems();
     //            save();
    }


    void ListBoxDemo_Loaded(object sender, RoutedEventArgs e)
    {
        FrameworkElement element = (FrameworkElement)sender;
        element.Loaded -= ListBoxDemo_Loaded;
        scrollViewer = FindChildOfType<ScrollViewer>(element);
        if (scrollViewer == null)
        {
            throw new InvalidOperationException("ScrollViewer not found.");
        }

        Binding binding = new Binding();
        binding.Source = scrollViewer;
        binding.Path = new PropertyPath("VerticalOffset");
        binding.Mode = BindingMode.OneWay;
        this.SetBinding(ListVerticalOffsetProperty, binding);
    }

     private static  void OnListVerticalOffsetChanged(DependencyObject obj,           
       DependencyPropertyChangedEventArgs e)
    {
        MainPage page = obj as MainPage;
        ScrollViewer viewer = page.scrollViewer;

        //Checks if the Scroll has reached the last item based on the ScrollableHeight
        bool atBottom = viewer.VerticalOffset >= viewer.ScrollableHeight;

        if (atBottom)
        {
            //ViewModel will be better........
            //int Count = page.ListBoxDemo.Items.Count;
            //int end = Count + 10;
            //for (int i = Count; i < end; i++)
            //{
            //    page.ListBoxDemo.Items.Add("Dummy Item " + i);
            //}



                try
                {
                    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
                    {
                        using (IsolatedStorageFileStream stream = myIsolatedStorage.OpenFile("People.xml", FileMode.Open))
                        {

                            XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<Discrip>));
                            ObservableCollection<Discrip> data = (ObservableCollection<Discrip>)serializer.Deserialize(stream);
                              lst =data;
                              if (data.Count() < 50)
                              {
                                  for (int i = 0; i < data.Count(); i++)
                                  {
                                      page.save(lst);
                                      lst.Add(new Discrip { date = "" + i + data.ElementAt(i).date, Imagee = data.ElementAt(i).Imagee, ImageSource = data.ElementAt(i).ImageSource, link = data.ElementAt(i).link, Detail = data.ElementAt(i).Detail, header = data.ElementAt(i).header, Title = "" + lst.Count() + data.ElementAt(i).Title });
                                  }
                                  //   page. ListBoxDemo.ItemsSource = lst;
                                  //   MainPage p = new MainPage();

                              }

                        }
                    }
                }
                catch
                {
                    //add some code here
                }


        }
    }

      void save(ObservableCollection<Discrip> lst)
{
    XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();
    xmlWriterSettings.Indent = true;

    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
    {
        using (IsolatedStorageFileStream stream = myIsolatedStorage.OpenFile("People.xml", FileMode.Create))
        {
            XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<Discrip>));
            using (XmlWriter xmlWriter = XmlWriter.Create(stream, xmlWriterSettings))
            {
                serializer.Serialize(xmlWriter, lst);
                AddDummyItems();

            }
        }
    }
}
    void AddDummyItems()
    {
        try
        {
            using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                using (IsolatedStorageFileStream stream = myIsolatedStorage.OpenFile("People.xml", FileMode.Open))
                {

                    XmlSerializer serializer = new XmlSerializer(typeof(ObservableCollection<Discrip>));
                    ObservableCollection<Discrip> data = (ObservableCollection<Discrip>)serializer.Deserialize(stream);
                    //   lst = lst;
                    list = data;
                  //  MainPage page = new MainPage();
                  //  list.Add(lst);
                    ListBoxDemo.ItemsSource = list;

                }
            }
        }
        catch
        {
            //add some code here
        }
    }

    public readonly DependencyProperty ListVerticalOffsetProperty = DependencyProperty.Register("ListVerticalOffset", typeof(double), typeof(MainPage),
        new PropertyMetadata(new PropertyChangedCallback(OnListVerticalOffsetChanged)));

    public double ListVerticalOffset
    {
        get { return (double)this.GetValue(ListVerticalOffsetProperty); }
        set { this.SetValue(ListVerticalOffsetProperty, value); }
    }

    /// <summary>
    /// Finding the ScrollViewer
    /// </summary>
    /// <typeparam name="T"></typeparam>
    /// <param name="root"></param>
    /// <returns></returns>
    static T FindChildOfType<T>(DependencyObject root) where T : class
    {
        var queue = new Queue<DependencyObject>();
        queue.Enqueue(root);

        while (queue.Count > 0)
        {
            DependencyObject current = queue.Dequeue();
            for (int i = VisualTreeHelper.GetChildrenCount(current) - 1; 0 <= i; i--)
            {
                var child = VisualTreeHelper.GetChild(current, i);
                var typedChild = child as T;
                if (typedChild != null)
                {
                    return typedChild;
                }
                queue.Enqueue(child);
            }
        }
        return null;
    }
}
   } 

Мой Xaml

            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Border  BorderBrush="Black" CornerRadius="8" BorderThickness="1" HorizontalAlignment="Stretch" Name="border">

                        <Grid   HorizontalAlignment="Stretch" Name="grid1" VerticalAlignment="Stretch">

                            <Grid.RowDefinitions>
                                <RowDefinition Height="0*" />
                                <RowDefinition Height="100*" />
                            </Grid.RowDefinitions>
                            <Image Height="78" HorizontalAlignment="Left" Margin="13,12,0,0" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="92" Grid.Row="1" Source="{Binding ImageSource}" />
                            <TextBlock Foreground="White" Height="80" HorizontalAlignment="Left" Margin="111,12,0,0" Name="textBlock1" Text="{Binding Title}" VerticalAlignment="Top" Width="280" TextWrapping="Wrap" Grid.Row="1" />
                            <Image Grid.Row="1" Height="75" HorizontalAlignment="Left" Margin="380,12,0,0" Name="image2" Stretch="Fill" VerticalAlignment="Top" Width="73"  Source="/WindowsPhoneApplication7;component/Images/appbar.transport.play.rest.png" />

                            <TextBlock  Foreground="White" Grid.Row="1" Height="20" HorizontalAlignment="Left" Margin="111,88,0,0" Name="textBlock2" Text="{Binding date}" VerticalAlignment="Top" Width="190" FontSize="11" />
                        </Grid>

                    </Border>
                </DataTemplate>

            </ListBox.ItemTemplate>

        </ListBox>