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Revision as of 11:15, 30 January 2012 by manikantan (Talk | contribs)

Saving application preferences in Windows Phone

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This article explains how to save and load application preferences on Windows Phone 7 devices.


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Article Metadata
Tested with
Devices(s): Nokia Lumia 800"
CompatibilityArticle
Keywords: IsolatedStorageSettings -->
Created: (06 Sep 2013)
Last edited: manikantan (30 Jan 2012)

Contents

Introduction

In most or applications, saving user preferences is a common task. Common scenarios can be - Saving user's country in applications like Groupon, saving and loading top scores in games, saving user's preferences for sounds in a game. This articles discusses the procedure to save and load such user preferences.

Class

The class IsolatedStorageSettings comes to our rescue to save and load these preferences. The class helps you store dictionary-like, key-value store. IsolatedStorageSettings are preserved across device reboots. The settings are stored inside the Isolated Storage space of an application, hence inaccessible to other applications. Hence, we can claim they are secure.

Sample Application

Below, we create a simple application that stores the user's preferences in a game. Three elements such as Game Music, Timed Mode and Difficulty level have been identified as preferences for a game. Since Game Music and Timed Mode essentially hold boolean values, in the UI of application we use ToggleSwitch. ToggleSwitch does not come along with the Windows Phone SDK and has to be downloaded separately from codeplex and installed. This has been described here. This is rich resource for Windows Phone controls. Lets create the user interface for the settings page in XAML.

<phone:PhoneApplicationPage 
x:Class="Pref.MainPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:toolbox="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"
mc:Ignorable="d" d:DesignWidth="480" d:DesignHeight="768"
FontFamily="{StaticResource PhoneFontFamilyNormal}"
FontSize="{StaticResource PhoneFontSizeNormal}"
Foreground="{StaticResource PhoneForegroundBrush}"
SupportedOrientations="Portrait" Orientation="Portrait"
shell:SystemTray.IsVisible="True">
 
<!--LayoutRoot is the root grid where all page content is placed-->
<Grid x:Name="LayoutRoot" Background="Transparent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
 
<!--TitlePanel contains the name of the application and page title-->
<StackPanel x:Name="TitlePanel" Grid.Row="0" Margin="12,17,0,28">
<TextBlock x:Name="ApplicationTitle" Text="MY GAME" Style="{StaticResource PhoneTextNormalStyle}"/>
<TextBlock x:Name="PageTitle" Text="Settings" Margin="9,-7,0,0" Style="{StaticResource PhoneTextTitle1Style}"/>
</StackPanel>
 
<!--ContentPanel - place additional content here-->
<Grid x:Name="ContentPanel" Grid.Row="1" Margin="12,0,12,0">
 
<toolbox:ToggleSwitch Name="gameMusic" Header="Game Music"></toolbox:ToggleSwitch>
<toolbox:ToggleSwitch Name="timed" Header="Timed Mode" Margin="6,119,6,371"></toolbox:ToggleSwitch>
 
<Slider Height="84" HorizontalAlignment="Left" Margin="12,310,0,0" Name="slider1" VerticalAlignment="Top" Width="418" Value="1" Minimum="1" />
<TextBlock Height="30" HorizontalAlignment="Left" Margin="12,274,0,0" Name="Difficulty" Text="Difficulty Level" VerticalAlignment="Top" Width="135" />
</Grid>
</Grid>
 
<!--Sample code showing usage of ApplicationBar-->
<!--<phone:PhoneApplicationPage.ApplicationBar>
<shell:ApplicationBar IsVisible="True" IsMenuEnabled="True">
<shell:ApplicationBarIconButton IconUri="/Images/appbar_button1.png" Text="Button 1"/>
<shell:ApplicationBarIconButton IconUri="/Images/appbar_button2.png" Text="Button 2"/>
<shell:ApplicationBar.MenuItems>
<shell:ApplicationBarMenuItem Text="MenuItem 1"/>
<shell:ApplicationBarMenuItem Text="MenuItem 2"/>
</shell:ApplicationBar.MenuItems>
</shell:ApplicationBar>
</phone:PhoneApplicationPage.ApplicationBar>-->
 
</phone:PhoneApplicationPage>


This gives us an interface like this.

Application UI

Code Behind

Instead of having a save and load button on the UI, its more intuitive to simply load and save preferences when the user navigates TO and FROM the page. Hence in the MainPage.xaml.cs Class, we override the OnNavigatedTo() and OnNavigatedFrom() methods.

namespace Pref
{
public partial class MainPage : PhoneApplicationPage
{
private IsolatedStorageSettings settings;
// Constructor
public MainPage()
{
InitializeComponent();
settings = IsolatedStorageSettings.ApplicationSettings;
}
 
protected override void OnNavigatedTo(NavigationEventArgs e)
{
System.Diagnostics.Debug.WriteLine("into the app");
try
{
System.Diagnostics.Debug.WriteLine("Retrieving values");
gameMusic.IsChecked = (bool)settings["gamemusic"];
timed.IsChecked = (bool)settings["timed"];
slider1.Value = ( Int16)settings["diff"];
 
}
catch(KeyNotFoundException ex)
{
System.Diagnostics.Debug.WriteLine("First Time using the app");
settings.Add("timed", false);
settings.Add("gamemusic", false);
settings.Add("diff", 1);
settings.Save();
 
}
 
}
protected override void OnNavigatedFrom(NavigationEventArgs e)
{
System.Diagnostics.Debug.WriteLine("Exiting, so save now");
settings["timed"] = timed.IsChecked;
settings["diff"] = (Int16) slider1.Value;
settings["gamemusic"] = gameMusic.IsChecked;
settings.Save();
}
}
}

So as you can observe, I am accessing the values in the IsolatedStorageSettings in the form of Key Value pairs. Remember to cast the values when retrieving or saving to this file. It is also reminded that Save() method needs to be called to store or flush these values. If a key is non-existent in the IsolatedStorageSettings, then it may raise KeyNotFoundException.


Summary

This article describes one of the fundamental tasks in application development - saving and loading user preferences. This is can be extended to many minimal storage use-cases such as top scores in games.

Further Reading

1. How to: Store and Retrieve Application Settings Using Isolated Storage 2. IsolatedStorageSettings class


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