WP7逻辑删除-简单的实践

Question

我有一个数据绑定的xml阅读器。MainPage连接到DetailsPage:当用户点击主页中的姓名时，她会获得该姓名的详细信息(年龄、性别、出生日期等)。在DetailsPage中。

我遇到了盗用自动取款机的麻烦。当我点击窗口按钮，然后点击后退按钮，我进入一个空的DetailsPage。

解决这个问题的最简单方法是什么？我尝试使用TombstoneHelper，但它也显示为空页面。

DetailsPage.xaml

        <controls:PanoramaItem Header="" Margin="0,0,0,80">
            <ScrollViewer>
                <StackPanel>
                    <TextBlock TextWrapping="Wrap" Width="432" Style="{StaticResource PhoneTextExtraLargeStyle}" Margin="0,0,0,10" d:LayoutOverrides="Width" Foreground="#DEFFFFFF"><Run Text="Personal D"/><Run Text="e"/><Run Text="tails"/></TextBlock>
                    <StackPanel HorizontalAlignment="Left" Width="432" Orientation="Horizontal">
                        <TextBlock TextWrapping="Wrap" Margin="20,0,7,0" Foreground="#DEFFFFFF"><Run Text="Name"/><Run Text=":"/></TextBlock>
                        <TextBlock x:Name="username" TextWrapping="Wrap" Text="{Binding Name}" Foreground="#DEFFFFFF" />
                    </StackPanel>
                    <StackPanel HorizontalAlignment="Left" Width="432" Orientation="Horizontal">
                        <TextBlock TextWrapping="Wrap" Margin="20,0,7,0" Foreground="#DEFFFFFF"><Run Text="Age"/><Run Text=":"/></TextBlock>
                        <TextBlock x:Name="age" TextWrapping="Wrap" Text="{Binding Age}" Foreground="#DEFFFFFF"/>
                    </StackPanel>
                    <StackPanel HorizontalAlignment="Left" Width="432" Orientation="Horizontal">
                        <TextBlock TextWrapping="Wrap" Margin="20,0,7,0" Foreground="#DEFFFFFF"><Run Text="Nationality"/><Run Text=":"/></TextBlock>
                        <TextBlock x:Name="country" TextWrapping="Wrap" Text="{Binding Country}" Foreground="#DEFFFFFF"/>
                    </StackPanel>
                    <StackPanel HorizontalAlignment="Left" Width="432" Orientation="Horizontal">
                        <TextBlock TextWrapping="Wrap" Margin="20,0,7,0" Foreground="#DEFFFFFF"><Run Text="Country of Birth"/><Run Text=":"/></TextBlock>
                        <TextBlock x:Name="cobirth" TextWrapping="Wrap" Text="{Binding Cobirth}" Foreground="#DEFFFFFF"/>
                    </StackPanel>
                    <StackPanel HorizontalAlignment="Left" Width="432" Orientation="Horizontal">
                        <TextBlock TextWrapping="Wrap" Margin="20,0,7,0" Foreground="#DEFFFFFF"><Run Text="Place of Birth"/><Run Text=":"/></TextBlock>
                        <TextBlock x:Name="fobirth" TextWrapping="Wrap" Text="{Binding Pobirth}" Foreground="#DEFFFFFF"/>
                    </StackPanel>
                </StackPanel>
            </ScrollViewer>
        </controls:PanoramaItem>

DetailsPage.cs

使用TombstoneHelper；

    public User()
    {
        InitializeComponent();
        SupportedOrientations = SupportedPageOrientation.Portrait;
    }
    protected override void OnNavigatedFrom(System.Windows.Navigation.NavigationEventArgs e)
    {
        base.OnNavigatedFrom(e);

        this.SaveState();  // <- first line
    }

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

        this.RestoreState();  // <- second line
    }

Mainpage.Cs

    private void UserListBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (e.AddedItems.Count > 0)
        {
            NavigationService.Navigate(new Uri("/DetailsPage.xaml", UriKind.Relative));

            FrameworkElement root = Application.Current.RootVisual as FrameworkElement;
            root.DataContext = (RosterItem)e.AddedItems[0];
            ((ListBox)sender).SelectedIndex = -1;

        }
    }

Answer 1

在所有条件都相同的情况下，Tombstone helper应该可以正常工作。请记住，您需要为Tombstone帮助器命名控件(使用x:Name属性)才能访问它们。还要确保在NavigatedFrom()方法中调用SaveState()，在NavigatedTo()中调用RestoreState() (而不是反过来)。

如果不是这样，那么一定是代码中的其他地方出了问题。如果您发布代码的相关部分，我们可能会有所帮助。