iOS Crash: NullReferenceException after VS 2019 update.

[busec0]

I'm encountering an issue on iOS after the update to VS 2019. I'm using XF 3.6.0 and Xamarin.iOS 12.8.0.0. It happens when an instance of TKCustomMap gets disposed.

Within the iOS's TKCustomMapRenderer the app crashes with NullReferenceException when base.Dispose(disposing) is called in the overridden method: protected override void Dispose(bool disposing)

It can easily be reproduced by pushing a page which contains a Map instance and then popping it from the Navigation.

You can download a sample app from here:

TKMaps_DisposeFailsSampleProject.zip

It opens two different pages:

1. A Map Page using the default TKCustomMap implementation. Pushing and then popping the page will crash with NullReferenceException.
2. Custom Maps Page. I've manually added the content from TKCustomMapRenderer in my iOS project (named it MapViewRenderer.cs) and commented out the call to base.Dispose() within the protected override void Dispose(bool disposing). App wont crash now.

The same issue is also opened here:
xamarin/xamarin-macios#5899

[pamela032709]

Have you found any workaround for this issue?

[busec0]

Unfortunately no. In my debug builds I've manually added the iOS map view renderer and commented out the call to base.Dispose() (you can check my sample app, did the same thing there).

It will prevent it from crashing and let me work "normally", but it is not a reliable solution for production builds.

I'm still waiting for a fix and hope we'll get one soon, might be an issue with Xamarin.iOS as it worked just fine with the previous version.

[pamela032709]

same here! android is fine as well just tested. lets just hope they can provide a fix. but not to enthusiastic about it since they havent provide any update or release in about a year.

…

On Apr 18, 2019, at 1:56 PM, Bulzan Sergiu ***@***.***> wrote: Unfortunately no. In my debug builds I've manually added the iOS map view renderer and commented out the call to base.Dispose() (you can check my sample app, did the same thing there). It will prevent it from crashing and let me work "normally", but it is not a reliable solution for production builds. I'm still waiting for a fix and hope we'll get one soon, might be an issue with Xamarin.iOS as it worked just fine with the previous version. — You are receiving this because you commented. Reply to this email directly, view it on GitHub, or mute the thread.

[busec0]

Closing this as it was a Xamarin.iOS bug, the fix is ready and will soon be released.

Check for more info:
xamarin/xamarin-macios#5899