Question

我最近遇到了App.Current.Terminate方法，我想在应用程序中使用它。但是，在调用它之前，我需要保存一些数据。出于某种原因，即使保存似乎显示为有效，一旦应用程序终止，旧设置将被恢复。我无法弄清楚发生了什么。我有一个ListPicker，我正在尝试使用Jeff Wilcox的ThemeManager在光明和黑暗之间更改我的应用程序中的主题设置。

SettingsPage.xaml

<Grid.Resources>
        <DataTemplate x:Name="PickerItemTemplate">
            <StackPanel Tap="stk_Tap">
                <TextBlock Text="{Binding Name}"/>
            </StackPanel>
        </DataTemplate>
    </Grid.Resources>

...

<toolkit:ListPicker x:Name="ThemeListPicker" Header="Theme"
                                        ItemTemplate="{StaticResource PickerItemTemplate}"/>

SettingsPage.xaml.cs

List<Theme> themeList;
private int currentThemeIndex;

protected override void OnNavigatedTo(NavigationEventArgs e)
    {
        base.OnNavigatedTo(e);

        themeList = new List<Theme>();
        themeList.Add(new Theme() { Name = "light", name = "light" }); //Name subject to change
        themeList.Add(new Theme() { Name = "dark", name = "dark" }); //Name subject to change
        ThemeListPicker.ItemsSource = themeList;

        //make sure ThemeListPicker shows current theme when NavigatedTo
        if (Settings.LightTheme.Value)
        {
            ThemeListPicker.SelectedIndex = 0;
            currentThemeIndex = 0;
        }                
        else
        {
            ThemeListPicker.SelectedIndex = 1;
            currentThemeIndex = 1;
        }                
    }

private void stk_Tap(object sender, System.Windows.Input.GestureEventArgs e)
    {
        if (ThemeListPicker.SelectedIndex != -1)
        {
            //avoid asking the question if the selected item is the same as the current item
            //doesn't quite work properly? Skips when the item is changed for the first time
            if(ThemeListPicker.SelectedIndex != currentThemeIndex)
            {
                MessageBoxResult result = MessageBox.Show("The app must be restarted to apply theme changes."", "", MessageBoxButton.OKCancel);
                if (result == MessageBoxResult.OK)
                {
                    var selectedItem = (Theme)(sender as StackPanel).DataContext;

                    switch (selectedItem.name)
                    {
                        case "light":
                            Settings.LightTheme.Value = true;
                            currentThemeIndex = 0;
                            break;
                        case "dark":
                            Settings.LightTheme.Value = false;
                            currentThemeIndex = 1;
                            break;
                        default:
                            Settings.LightTheme.Value = true;
                            currentThemeIndex = 0;
                            break;
                    }

                    Terminate();
                }
            }
}

private void Terminate()
    {
        App.Current.Terminate();
    }

Theme.cs

public class Theme
{
    public string Name
    {
        get;
        set;
    }

    public string name //name to use in determining current theme
    {
        get;
        set;
    }
}

Settings.cs //将键/值对写入IsoStore

//Theme - set to true by default
public static readonly Setting<bool> LightTheme = new Setting<bool>("LightTheme", true);

App.xaml.cs

public App()
    {
        ...

        //Theme Manager
        if (Settings.LightTheme.Value)
            ThemeManager.ToLightTheme();
        else
            ThemeManager.ToDarkTheme();

        ...
    }

主要问题是主题永远不会改变。我在App.xaml.cs中设置了一个断点，以检查应用程序加载时Settings.LightTheme.Value的当前值，该值始终保持为true，将应用程序设置为灯光主题。在SettingsPage.xaml.cs中，当用户选择ListPicker中的浅色或深色选项时，我检测到Settings.LightTheme.Value的值在true和false之间切换。紧接着，由于用户必须在MessageBox上选择OK以重新启动应用程序，应用程序将被终止。重新启动后，Settings.LightTheme.Value为真。我不知道如何解决这个问题？

Answer 1

终止前请致电 IsolatedStorageSettings.Save()。

Answer 2

在App.xaml.cs中，可以找到以下方法。只需将“主题保存”代码添加到此方法中即可。

// Code to execute when the application is closing (eg, user hit Back)
// This code will not execute when the application is deactivated
private void Application_Closing(object sender, ClosingEventArgs e)
{
    //theme saving code goes here           
}

如何正确终止应用程序并保存数据

2 个答案: