how to override windows back button in windows pho

问题:

I need to ovveride the windows back button when i am clicking from my application .I tried 2 method below but it is not working in windows phone 8 ?

methods 1)

protected override void OnBackKeyPress(System.ComponentModel.CancelEventArgs e)

            {

           e.Cancel = true;

           var result = MessageBox.Show("Do you want to exit?", "Attention!",
                                      MessageBoxButton.OKCancel);

        if (result == MessageBoxResult.OK)
        {
           // base.OnBackKeyPress(e);
            return;
        }
        e.Cancel = true;
    }

method 2 )

a) wrote this in xaml heading

BackKeyPress="MyBackKeyPress"

b) Initlize this in constructor

 BackKeyPress += OnBackKeyPress;

c) and call this method

   private void MyBackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
    {
        e.Cancel = true; //tell system you have handled it
        //you c
    }

the two of the methods are not working . when i was clicked the back button the app destroyed and unable to get the control of backbutton . Any help ?

回答1:

As per certification requirements it is not recommended to override the back button -

Pressing the Back button from the first screen of an app must close the app.

http://msdn.microsoft.com/en-us/library/windowsphone/develop/hh184840%28v=vs.105%29.aspx

You can try this code

protected override void OnBackKeyPress(CancelEventArgs e)
{
    if(MessageBox.Show("Are you sure you want to exit?","Confirm Exit?", 
                            MessageBoxButton.OKCancel) != MessageBoxResult.OK)
    {
        e.Cancel = true; 

    }
}

回答2:

Try this one, which works for me

Step 1 : in XAML

BackKeyPress="PhoneApplicationPage_BackKeyPress"

Step 2 : in C#

private void PhoneApplicationPage_BackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
        {
            MessageBoxResult mRes = MessageBox.Show("Would you like to exit?", "Exit", MessageBoxButton.OKCancel);
            if (mRes == MessageBoxResult.OK)
            {
                NavigationService.GoBack();
            }
            if (mRes == MessageBoxResult.Cancel)
            {
                e.Cancel = true;
            }
        }

回答3:

In your MyBackKeyPress method, throw a new exception to close the app in the runtime and return to the phone's menu. I don't know if this is a good way to achieve it, but this definitely solves the problem.

private void MyBackKeyPress(object sender, System.ComponentModel.CancelEventArgs e)
{
     throw new Exception();
}

Test this on emulator/device without Dubuggingin Visual Studio and you will see that your app closes.

回答4:

I tried the same . but it is not working . i put the breakpoints inside the code and also found its not entering or not calling the function when i click back button . – user1703145 45 mins ago

You haven't forgotten to bind this event in XAML?

<phone:PhoneApplicationPage ..... BackKeyPress="phoneApplicationPage_BackKeyPress">