在App.xaml.cs中传递全局对象的引用

Question

I am trying to implement a global object which stores every parameter that I can pass between pages. My object is called AppObject. I can declare it in my mainpage.xaml.cs and then pass it through reference using

Page.Navigate(typeof(anotherpage), AppObject);

However, I would like to save the objects to file through the on_suspending event. How can I pass this parameter to the on_suspending event or is there anyway for me to declare this AppObject in the app.xaml.cs and then pass it to the mainpage.xaml.cs?

My App.xaml.cs

AppObject AppObject = new AppObject();

    /// <summary>
    /// Initializes the singleton application object.  This is the first line of authored code
    /// executed, and as such is the logical equivalent of main() or WinMain().
    /// </summary>
    public App()
    {
        this.InitializeComponent();
        this.Suspending += this.OnSuspending;
        Windows.Phone.UI.Input.HardwareButtons.BackPressed += HardwareButtons_BackPressed;
    }

...more code

    /// <summary>
    /// Invoked when application execution is being suspended.  Application state is saved
    /// without knowing whether the application will be terminated or resumed with the contents
    /// of memory still intact.
    /// </summary>
    /// <param name="sender">The source of the suspend request.</param>
    /// <param name="e">Details about the suspend request.</param>
    private async void OnSuspending(object sender, SuspendingEventArgs e)
    {
        var deferral = e.SuspendingOperation.GetDeferral();

        // TODO: Save application state and stop any background activity

        //I want to write to file here and be able to refereence to the AppObject which I pass around.

        deferral.Complete();
    }

Answer 1

In App.xaml.cs, make sure the objects you need are public. Say you have something like this:

public AppObject appObject = new AppObject();

Now, in MainPage.xaml.cs, you just have to create the objects of the same type you want to pass. Then, create another object that has the reference to the App like this:

var appReference = App.Current as App;
AppObject objectInMain = appReference.appObject;

Now you have another object in MainPage.xaml.cs, that is the exact copy of the one in App.xaml.cs. You've just effectively passed data between two pages. You can create a reference to the App in any page as shown above and use the variables declared in App.xaml.cs in that page.