异步无法按 Windows Phone 8.1 的后退键

Question

private async void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
    var msg = new MessageDialog("Confirm Close");
    var okBtn = new UICommand("OK");
    var cancelBtn = new UICommand("Cancel");
    msg.Commands.Add(okBtn);
    msg.Commands.Add(cancelBtn);
    IUICommand result = await msg.ShowAsync();
}

主要问题是按下后退按钮时，消息会显示 1-2 秒，然后应用会关闭。怎么办？

Answer 1

我认为异步工作正常，您没有将 e.Handeled 设置为 true，这意味着进一步 BackPressed事件被处理并且应用程序退出。像这样尝试：

private async void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
    e.Handled = true;
    var msg = new MessageDialog("Confirm Close");
    var okBtn = new UICommand("OK");
    var cancelBtn = new UICommand("Cancel");
    msg.Commands.Add(okBtn);
    msg.Commands.Add(cancelBtn);
    IUICommand result = await msg.ShowAsync();
}

另请记住，您的应用必须能够通过 BackButton 退出，因此必须以某种方式修改上面的代码。

Answer 2

试试这个代码：

var messgeDialog = new MessageDialog("Are you sure you want to close", "Are you sure?");
                    messgeDialog.Commands.Add(new UICommand("Yes"));
                    messgeDialog.Commands.Add(new UICommand("No"));
                    messgeDialog.DefaultCommandIndex = 0;
                    messgeDialog.CancelCommandIndex = 1;
                    var result = await messgeDialog.ShowAsync();
                    if (result.Label.Equals("Yes"))
                    {
                    //Do something when a user pressed yes
                    }
                    else
                    {
                    //User pressed no
                    }

异步无法按 Windows Phone 8.1 的后退键

async not working on pressing back key of Windows Phone 8.1

c#

windows-phone-8.1