Why the page's destructor never called?

Question

[Xamain.Forms Android]
I create a blank page，add destructor like this:

        ~EmptyPage()  
        {  
            Console.WriteLine("Empty page destructor running..............");  
        }  
  

And then I use:

                var page0 = new EmptyPage();  
                await Shell.Current.Navigation.PushAsync(page0);  
  

to open the page, and I manully close the page, I hope console will output "Empty page destructor running..............“, but nothing.
It seemd that the destructor never called, why?

My real question is, I am using "MessagingCenter.Subscribe" in the EmptyPage, and I found after close the page, the MessagingCenter still working in memory, it will cause memory leak, right?
I want to Unsubscribe in the destructor, but destructor never called, so what is the best way to Unsubscribe?
I try "OnDisappearing" event, but if I open new page on EmptyPage, it will rise OnDisappearing on EmptyPage, that was not I wanted...
I want Unsubscribe only when EmptyPage is closed, any suggestion?

Answer 1

Hello,

You could refer to this official documentation Finalizers (C# Programming Guide), and find the following contents:

Finalizers cannot be defined in structs. They are only used with classes.
A class can only have one finalizer.
Finalizers cannot be inherited or overloaded.
Finalizers cannot be called. They are invoked automatically.
A finalizer does not take modifiers or have parameters.

In MAUI, it is more recommended to use BackButtonBehavior to unsubscribe the MessagingCenter.

You could refer to the following code:

In EmptyPage.xaml:

   <Shell.BackButtonBehavior>   
       <BackButtonBehavior Command="{Binding TestCommand}"/>  
   </Shell.BackButtonBehavior>  

In your ViewModel.cs:

   TestCommand = new Command(Unsubscribe); // the Unsubscribe method is your own method to unsubscribe MessagingCenter  

Best Regards,

Alec Liu.

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