Windows Phone 7 : Isolated Storage - Modifying Settings of Your Application

1. Problem

You want to locally save some settings about your application and then retrieve those settings later.

2. Solution

You must use the IsolatedStorageSettings class to access your application settings adding and deleting keys, like a dictionary.

3. How It Works

IsolatedStorageSettings enables you to easily and locally store user-specific data as key/value pairs in the object IsolatedStorageFile. You will see that the use of IsolatedStorageSettings is equal to the use of a dictionary <TKey, TValue>.

4. The Code

A type of push notification is toast notification . that requires that your application to be accepted and published on Marketplace must ask users whether they want to be notified with them. What better place for your application to store the user's choice than in the application settings?

To create this recipe, we have not focused on the application's user interface, but on the page of settings. Suppose that our application use notifications and sounds and we want to give to your user the possibility to disable or enable them

...
<phone:PhoneApplicationPage.ApplicationBar>
  <shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
    <shell:ApplicationBarIconButton x:Name="SaveSettingsButton"
      IconUri="/icons/appbar.save.rest.jpg"
      Text="Save" Click="SaveSettingsButton_Click" />
  </shell:ApplicationBar>
</phone:PhoneApplicationPage.ApplicationBar>

<Grid x:Name="LayoutRoot" Background="Transparent">
  <Grid.RowDefinitions>
    <RowDefinition Height="Auto"/>
    <RowDefinition Height="*"/>
  </Grid.RowDefinitions>

  <StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
    <TextBlock x:Name="PageTitle" Text="Settings" Style="{StaticResource
      PhoneTextNormalStyle}"/>
  </StackPanel>
  <ScrollViewer x:Name="ContentPanel" Margin="12,0,12,0" Grid.Row="1" >
    <StackPanel>
      <toolkit:ToggleSwitch Header="Toast Notification" x:Name="ToastSwitch"  />
      <toolkit:ToggleSwitch Header="Sounds" x:Name="SoundsSwitch" />
    </StackPanel>
  </ScrollViewer>

					  

This XAML, inserted into the template of your page, will show an interface similar to that in Figure 1. We say similar because you might not be using the same icon or the same control to check the settings. For example, you could have chosen a check box or toggle button.

Figure 1. The Settings page

In the code-behind, of the page Settings, within the constructor you subscribe to the loaded event with Settings_Loaded event handler:

public Settings()
        {
            InitializeComponent();
            this.Loaded += new RoutedEventHandler(Settings_Loaded);
        }

And you define two class-level constant strings:

...
private const string _toastEnabledKey = "ToastEnabled";
private const string _soundsEnabledKey = "SoundsEnabled";
...

Why do you do this? Because basically, by accessing settings through a dictionary, you will have a number of key/value pairs that could potentially include everything.

The event handler Settings_Loaded will retrieve your settings and change the value of the switch with the following code:

void Settings_Loaded(object sender, RoutedEventArgs e)
{
  if (IsolatedStorageSettings.ApplicationSettings.Contains(_toastEnabledKey))
  {
    var toast = IsolatedStorageSettings.ApplicationSettings[_toastEnabledKey].ToString();
    this.ToastSwitch.IsChecked = bool.Parse(toast);
  }
  if (IsolatedStorageSettings.ApplicationSettings.Contains(_soundsEnabledkey))
  {
    var sounds = IsolatedStorageSettings.ApplicationSettings[_soundsEnabledkey].ToString();
    this.SoundsSwitch.IsChecked = bool.Parse(sounds);
  }
}

					  

Line by line, what happens is as follows:

In this way, you have loaded the settings related to your application, and so now you can see how to save them, with the handler SaveSettingsButton_Click:

private void SaveSettingsButton_Click(object sender, EventArgs e)
{
  IsolatedStorageSettings.ApplicationSettings[_toastEnabledKey] =
     this.ToastSwitch.IsChecked;
  IsolatedStorageSettings.ApplicationSettings[_soundsEnabledkey] =
     this.SoundsSwitch.IsChecked;
}

The only thing to do to save a setting of the dictionary is assign a key and a value, then thinks at all the class IsolateStorageSetting. In order to pursue this exercise further, consider at this point using the settings to save the BPM of the metronome of our application 7Drum, for example.

5. Usage

Start the toast notification application by pressing F5 from Visual Studio. Open the Settings page. Change the settings and save them, thereby provoking the tombstoning of this application. Start the application again and open the Settings page to see that your settings have been saved.