[iOS] When navigating, the view is sometimes different from the ViewModel

[pdecostervgls]

Current behavior

After upgrading to Uno 3.11.6 we noticed a regression in the navigation flow. Our app suddenly decided to show the view of a entirely different page than was navigated towards, but the ViewModel was correct.
We reproduced this issue in our earlier used "deconstructed" version of the app, because we are confident that the issue lies in the configuration of our app, therefore a clean reproducable project was not created.

Observe the following .GIF demonstrating the issue.

• First we show the app and its "greek" pages independently
• Then we navigate back the page before the settings page
• Upon getting to the settings page, we show the Support page again, which is shown fine
• But when we open the Alpha page, we see the beta symbol, even though the CommandBar title and VM is correct.
• This happens with all other pages after that, until even the Delta page starts showing the contents of the settings page

Expected behavior

The loaded view should correspond to the requested page.

How to reproduce it (as minimally and precisely as possible)

As stated before, for hunting this issue down we used the stripped down "Deconstructed" version of our actual app. This should prove to be sufficient.

(project zip will be included once I can upload it on GitHub)

Workaround

No response

Works on UWP/WinUI

Yes

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia

NuGet package version(s)

Uno.UI: 3.11.6

Affected platforms

iOS

IDE

Visual Studio 2022

IDE version

17.0.1

Relevant plugins

No response

Anything else we need to know?

No response

[jeromelaban]

Thanks for the report.

Can you try adding the following : FrameworkTemplatePool.IsPoolingEnabled = false; in your app.xaml.cs and see if this helps ?

[pdecostervgls]

@jeromelaban Seems to have resolved it, seems its a bug in the pooling then?

[jeromelaban]

It's not necessarily a bug in the pooling, but rather with controls that are not aware that they can be reused. This is generally a problem if the content being reused if modified explicitly through code (instead of bindings).

Do you know what part of the UI is being incorrect ?

[pdecostervgls]

In my example, the entire page. The "Bound VM" is correct because in all cases it refers to {Binding}

[jeromelaban]

This could mean that the constructor is not invoked because the page or some of its contents is reused. Do you initialize the datacontext in the constructor by any chance ?

[pdecostervgls]

Not that I am aware of. The datacontext is being set in the XAML with DataContext="{Binding Alpha, Source={StaticResource Locator}}". Where Locator is of type ViewModelLocator

[jeromelaban]

We've made changes around pooling, which may have fixed this issue. If that's the case, let us know.