Question

I am trying to create a settings page for my windows phone 7 application and i am using this article as the basis http://msdn.microsoft.com/en-us/library/ff769510(v=vs.92).aspx so my application class is :

 public class AppSettings
{

    // Our isolated storage settings
    IsolatedStorageSettings isolatedStore;

    // The isolated storage key names of our settings
    const string CheckBoxSettingKeyName = "CheckBoxSetting";
    const string ListBoxSettingKeyName = "ListBoxSetting";
    const string RadioButton1SettingKeyName = "RadioButton1Setting";
    const string RadioButton2SettingKeyName = "RadioButton2Setting";
    const string RadioButton3SettingKeyName = "RadioButton3Setting";
    const string UsernameSettingKeyName = "UsernameSetting";
    const string PasswordSettingKeyName = "PasswordSetting";

    // The default value of our settings
    const bool CheckBoxSettingDefault = true;
    const int ListBoxSettingDefault = 0;
    const bool RadioButton1SettingDefault = true;
    const bool RadioButton2SettingDefault = false;
    const bool RadioButton3SettingDefault = false;
    const string UsernameSettingDefault = "";
    const string PasswordSettingDefault = "";

    /// <summary>
    /// Constructor that gets the application settings.
    /// </summary>
    public AppSettings()
    {
        try
        {
            // Get the settings for this application.
            isolatedStore = IsolatedStorageSettings.ApplicationSettings;

        }
        catch (Exception e)
        {
            Debug.WriteLine("Exception while using IsolatedStorageSettings: " + e.ToString());
        }
    }

    /// <summary>
    /// Update a setting value for our application. If the setting does not
    /// exist, then add the setting.
    /// </summary>
    /// <param name="Key"></param>
    /// <param name="value"></param>
    /// <returns></returns>
    public bool AddOrUpdateValue(string Key, Object value)
    {
        bool valueChanged = false;

        // If the key exists
        if (isolatedStore.Contains(Key))
        {
            // If the value has changed
            if (isolatedStore[Key] != value)
            {
                // Store the new value
                isolatedStore[Key] = value;
                valueChanged = true;
            }
        }
        // Otherwise create the key.
        else
        {
            isolatedStore.Add(Key, value);
            valueChanged = true;
        }

        return valueChanged;
    }


    /// <summary>
    /// Get the current value of the setting, or if it is not found, set the 
    /// setting to the default setting.
    /// </summary>
    /// <typeparam name="valueType"></typeparam>
    /// <param name="Key"></param>
    /// <param name="defaultValue"></param>
    /// <returns></returns>
    public valueType GetValueOrDefault<valueType>(string Key, valueType defaultValue)
    {
        valueType value;

        // If the key exists, retrieve the value.
        if (isolatedStore.Contains(Key))
        {
            value = (valueType)isolatedStore[Key];
        }
        // Otherwise, use the default value.
        else
        {
            value = defaultValue;
        }

        return value;
    }


    /// <summary>
    /// Save the settings.
    /// </summary>
    public void Save()
    {
        isolatedStore.Save();
    }


    /// <summary>
    /// Property to get and set a CheckBox Setting Key.
    /// </summary>
    public bool CheckBoxSetting
    {
        get
        {
            return GetValueOrDefault<bool>(CheckBoxSettingKeyName, CheckBoxSettingDefault);
        }
        set
        {
            AddOrUpdateValue(CheckBoxSettingKeyName, value);
            Save();
        }
    }


    /// <summary>
    /// Property to get and set a ListBox Setting Key.
    /// </summary>
    public int ListBoxSetting
    {
        get
        {
            return GetValueOrDefault<int>(ListBoxSettingKeyName, ListBoxSettingDefault);
        }
        set
        {
            AddOrUpdateValue(ListBoxSettingKeyName, value);
            Save();
        }
    }


    /// <summary>
    /// Property to get and set a RadioButton Setting Key.
    /// </summary>
    public bool RadioButton1Setting
    {
        get
        {
            return GetValueOrDefault<bool>(RadioButton1SettingKeyName, RadioButton1SettingDefault);
        }
        set
        {
            AddOrUpdateValue(RadioButton1SettingKeyName, value);
            Save();
        }
    }


    /// <summary>
    /// Property to get and set a RadioButton Setting Key.
    /// </summary>
    public bool RadioButton2Setting
    {
        get
        {
            return GetValueOrDefault<bool>(RadioButton2SettingKeyName, RadioButton2SettingDefault);
        }
        set
        {
            AddOrUpdateValue(RadioButton2SettingKeyName, value);
            Save();
        }
    }

    /// <summary>
    /// Property to get and set a RadioButton Setting Key.
    /// </summary>
    public bool RadioButton3Setting
    {
        get
        {
            return GetValueOrDefault<bool>(RadioButton3SettingKeyName, RadioButton3SettingDefault);
        }
        set
        {
            AddOrUpdateValue(RadioButton3SettingKeyName, value);
            Save();
        }
    }

    /// <summary>
    /// Property to get and set a Username Setting Key.
    /// </summary>
    public string UsernameSetting
    {
        get
        {
            return GetValueOrDefault<string>(UsernameSettingKeyName, UsernameSettingDefault);
        }
        set
        {
            AddOrUpdateValue(UsernameSettingKeyName, value);
            Save();
        }
    }

    /// <summary>
    /// Property to get and set a Password Setting Key.
    /// </summary>
    public string PasswordSetting
    {
        get
        {
            return GetValueOrDefault<string>(PasswordSettingKeyName, PasswordSettingDefault);
        }
        set
        {
            AddOrUpdateValue(PasswordSettingKeyName, value);
            Save();
        }
    }


}

Everything is working fine and i am able to update the settings value from a xaml settings page and i can access the setting values in my main application using

 IsolatedStorageSettings Settings; 
 Settings = IsolatedStorageSettings.ApplicationSettings;
 string checkboxvalue = (string)Settings["CheckBoxSetting"];

Now what i want is to be able to know when a value in the application settings is changed/updated , so that i can perform a action when settings are updated .

Answer 1

There are lots of ways you could do this but the easiest way to get startred is if you just query the settings when you need to know them.

The other simple alternative woudl be for your AppSettings object to raise events when something was changed and have the relevant other classes subscribe to them.