How to save changes in ListPicker Wp8

Question

In the ListPicker in my Windows Phone Application there is a List of items which a user can select one or more items and view those selected items. Until this point everything goes fine after this point I want to save the selected items on the same page. Now what happens when I close the application and starts it again there is no selected items saved. So my question is how can I save the changes made by the user? I don't want to save them in a separate file in the isolated storage actually. Thanks in advance.

Here is the XAML code:

<Border x:Name="Border"
        Background="{TemplateBinding Background}"
        BorderBrush="{TemplateBinding BorderBrush}"
        BorderThickness="{TemplateBinding BorderThickness}">
    <UserControl x:Name="UserControl">
        <StackPanel>
             <TextBlock x:Name="MultipleSelectionModeSummary" Margin="8 8 0 8" TextWrapping="Wrap" Width="300" HorizontalAlignment="Left"/>
             <Canvas x:Name="ItemsPresenterHost" MinHeight="46">
                 <ItemsPresenter x:Name="ItemsPresenter">
                     <ItemsPresenter.RenderTransform>
                         <TranslateTransform x:Name="ItemsPresenterTranslateTransform"/>
                     </ItemsPresenter.RenderTransform>
                 </ItemsPresenter>
             </Canvas>
        </StackPanel>         
    </UserControl>
</Border>
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
    <ScrollViewer Grid.Row="1">
        <toolkit:ListPicker Header="Print in colors"
                            SelectionMode="Multiple"
                            FullModeHeader="Colors"
                            CacheMode="BitMapCache"
                            x:Name="PrintInColors" 
        Template="{StaticResource ListPickerControlTemplate1}">
            <sys:String>Cyan</sys:String>
            <sys:String>Magenta</sys:String>
            <sys:String>Yellow</sys:String>
            <sys:String>Black</sys:String>
            <sys:String>White</sys:String>
            <sys:String>Blue</sys:String>
            <sys:String>Orange</sys:String>
            <sys:String>Gray</sys:String>
            <sys:String>Silver</sys:String>
        </toolkit:ListPicker>
    </ScrollViewer>
</Grid>

Here is the CS code:

private string Summarize(System.Collections.IList items)
{
    string str = "";
    if (null != items)
    {
        if (items.Contains("Cyan"))
        {
            str += "Cyan";
        }
        if (items.Contains("Magenta"))
        {
            str += "Mangeta";
        }
        if (items.Contains("Yellow"))
        {
            str += "Yellow";
        }
        if (items.Contains("Black"))
        {
            str += "Black";
        }
        if (items.Contains("White"))
        {
            str += "White";
        }
        if (items.Contains("Blue"))
        {
            str += "Blue";
        }
        if (items.Contains("Orange"))
        {
            str += "Orange";
        }
        if (items.Contains("Gray"))
        {
            str += "Gray";
        }
        if (items.Contains("Silver"))
        {
            str += "Silver";
        }
    }

    return str;
}

Answer 1

Please rethink. You need persistent storage to achieve that. Your application is installed and never get changed. I mean, all changes user made are in memory (RAM) and it will be unloaded/removed soon after the application closed.

Isolated storage is the most commonly used persistent storage for this purpose. And it is relatively simple as far as I can see (compared to saving to local or online database), so you really should consider saving the data to isolated storage.