Execute code after reloading page on Navigation.GoBack()

Question

I have a Window that only has one frame to show the different pages that my application has.

When a Page loads, it initializes several threads that deal with different elements of the UI. When I change the page with frame.Navigate(new NextPage()) I abort those threads, as it doesn't make sense to keep them running when the page is not in the foreground.

The problem comes when I make frame.GoBack(), since I have no way to relaunch those treads on the page because no code is executed when I return to the page.

There is something similar to the OnPause, OnStart, OnStop method of Android but for WPF and pages?

Something like the following:

public MainPage()
{
    InitializeComponent();
    var thread = new Thread(() => Code());
    thread.Start();
}

public Code()
{
    // Do Stuff
}

public Continue()
{
    thread.abort()
    frame.Navigate(new NextPage()) 
}

public OnPageReloaded()
{
    thread.start()
}

Some of these threads are for going back after a timeout. If I don't abort these threads, it will call frame.GoBack() when I'm on another page. — Lechucico, Feb 05 '20 at 09:01
so implement a logic to prevent them from calling GoBack. or abort some of them and pause the rest — Bizhan, Feb 05 '20 at 09:09

score 1 · Accepted Answer · answered Feb 05 '20 at 12:44

You should look into the Task Parallel Library (TPL) and create tasks instead of threads. Calling Abort() on a thread is bad practice.

As to your actual question, you could initialize your work in the Loaded event handler of the Page instead of doing it in the constructor:

public partial class Page1 : Page
{
    public Page1()
    {
        InitializeComponent();
        Loaded += Page1_Loaded;
    }

    private void Page1_Loaded(object sender, RoutedEventArgs e)
    {
        //start your tasks here...
    }
}

The Loaded event will be invoked each time your Page instance is being navigated to. There is also an Unloaded event that you can use to do cleanup.

Execute code after reloading page on Navigation.GoBack()

1 Answers1