Question

我正在使用Windows Phone 8.1应用。我想在用户按回键时显示消息。我知道代码，但出了点问题。 Visual Studio在MessageBox，MessageBoxResult。

下显示红线

如何在Windows Phone 8.1中显示消息？我认为在WP7操作系统之后它已经改变了。

这是我的代码示例。

public MainPage()
    {
        this.InitializeComponent();
        progRing.IsActive = true;
        Window.Current.SizeChanged += Current_SizeChanged;
        Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
        this.NavigationCacheMode = NavigationCacheMode.Required;
    }
    protected override void OnNavigatedTo(NavigationEventArgs e)
    {

    }

    private void HardwareButtons_BackPressed(object sender, Windows.Phone.UI.Input.BackPressedEventArgs e)
    {

    }

    protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
    {
        string caption = "Stop music and exit?";
        string message = "If you want to continue listen music while doing other stuff, please use Home key instead of Back key. Do you still want to exit?";
        e.Cancel = MessageBoxResult.Cancel == MessageBox.Show(message, caption, MessageBoxButton.OKCancel);

        base.OnBackKeyPress(e);
    }

Answer 1

通过Windows.Phone.UI.Input命名空间判断，您的目标是基于WinRT XAML的应用程序，而不是Silverlight WP8.1 在WinRT中没有MessageBox.Show（）方法您必须使用MessageDialog类加分是您可以自定义对话框上按钮的名称，并且该过程现在是异步的，这意味着它会在显示消息对话框时阻止您的应用程序运行

using Windows.UI.Popups;
...
MessageDialog dialogbox= new MessageDialog("Your message content", "title");
await dialogbox.ShowAsync();

JayDev的回答是完整和正确的

JayDev回答的一个问题是没有＆＃34;覆盖onBackKeyPress＆＃34;在WinRT中。这就是你要做的事情：

using Windows.Phone.UI.Input
...
protected override void OnNavigatedTo(NavigationEventArgs e)
        {
        //This should be written here rather than the contructor
        HardwareButtons.BackPressed += HardwareButtons_BackPressed;
        }

void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
        {
        //This is where all your 'override backkey' code goes
        //You can put message dialog and/or cancel the back key using e.Handled = true;
        }

protected override void OnNavigatingFrom(NavigatingCancelEventArgs e)
        {
        //remove the handler before you leave!
        HardwareButtons.BackPressed -= HardwareButtons_BackPressed;
        }

Answer 2

您需要使用MessageDialog而不是MessageBox。即

        MessageDialog message = new MessageDialog("my message");
        message.ShowAsync();

MessageDialog位于Windows.UI.Popups命名空间中。

具体到您可以使用的方案。

protected async override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)
{
    string caption = "Stop music and exit?";
    string message = "If you want to continue listen music while doing other stuff, please use Home key instead of Back key. Do you still want to exit?";

    MessageDialog msgDialog = new MessageDialog(message, caption);

    //OK Button
    UICommand okBtn = new UICommand("OK");
    msgDialog.Commands.Add(okBtn);

    //Cancel Button
     UICommand cancelBtn = new UICommand("Cancel");
     cancelBtn.Invoked = (s) => { e.Cancel = true; };
     msgDialog.Commands.Add(cancelBtn);

       //Show message
     await msgDialog.ShowAsync();

    base.OnBackKeyPress(e);
}

Answer 3

试试这个：

    MessageBoxResult res= MessageBox.Show(message,caption, MessageBoxButton.OKCancel);
    if (res == MessageBoxResult.OK)
    {
        //Do Action
    }
    else
    {
        //Do Action
    }

使用Windows Phone 8.1返回键按事件

3 个答案: