[Maui Embedded] DisconnectHandler not called when view is closed/disposed

[ultimategrandson]

Description

I am assuming this is because of my application utilizing Maui Embedded. I am creating a view as per the documentation. However, when I close the ViewController, it does not call DisconnectHandler.

I noticed this when I was implementing a Barcode Reader (using the ZXing MAUI library), the cleanup code that stops the camera from running is in the DisconnectHandler method. When the view is closed, it does not call this and the camera remains running.

Is there a way to cleanup these handlers?

Steps to Reproduce

No response

Link to public reproduction project repository

No response

Version with bug

7.0.96

Is this a regression from previous behavior?

Yes, this used to work in Xamarin.Forms

Last version that worked well

Unknown/Other

Affected platforms

iOS, I was not able test on other platforms

Affected platform versions

No response

Did you find any workaround?

No response

Relevant log output

No response

[ultimategrandson]

I have found a potential workaround, if I put this code in my ViewController, it will disconnect the handlers when I don't need them anymore:

foreach (var element in MauiPage.GetVisualTreeDescendants().OfType<IElement>()) element.Handler.DisconnectHandler();

Is this the recommended way of handling this?

[nll]

From this warning on the documentation it seems that is the expected behavior:

The DisconnectHandler method is intentionally not invoked by .NET MAUI. Instead, you must invoke it yourself from a suitable location in your app's lifecycle. For more information, see Native view cleanup.

(I was expecting it to be called as well, I only discover this recently)

from https://learn.microsoft.com/en-us/dotnet/maui/user-interface/handlers/create#create-the-platform-controls

[ultimategrandson]

I did not know this. Do any of the standard maui controls need disconnecting?

It would be nice if the handlers could indicate that they require cleanup, and then on the parent have a DisconnectAllHandlers that cleans up what needs to be cleaned up.

[PureWeen]

The problem is that we can't know when you want to disconnect the handler.

For example, if you're moving a view from one layout to another layout you might not want it to disconnect.

The guidance here is to use loaded/unloaded or the platform events related to being part of the visual tree to achieve what you want.

You know more about your life cycle than we do :-)

Hi @ultimategrandson. We have added the "s/needs-info" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. If it is closed, feel free to comment when you are able to provide the additional information and we will re-investigate.

[ultimategrandson]

The problem is that we can't know when you want to disconnect the handler.

For example, if you're moving a view from one layout to another layout you might not want it to disconnect.

The guidance here is to use loaded/unloaded or the platform events related to being part of the visual tree to achieve what you want.

You know more about your life cycle than we do :-)

I accept that we should do the cleanup, its just knowing what actually needs to be cleaned up.

Also, handlers don't implement IDisposable which I would normally intuit to meaning I need to manually clean up the resources of this myself.