ObjCRuntime.RuntimeException: 'Can't register the class {...} when the dynamic registrar has been linked away.'

[jeanplevesque]

I've recently updated an Uno class library and I now get the following error at runtime on iOS.
ObjCRuntime.RuntimeException: 'Can't register the class Nventive.ExtendedSplashScreen.ExtendedSplashScreen when the dynamic registrar has been linked away.'

I don't really understand what changed to cause this. The code changes mainly affect the Android platform.
The other change is in the pipelines: we now use hosted agents.
I suspect that the build difference comes from a different default behavior between VS 17.2.5 (previously used in our pipelines) and whatever version is installed on the windows-2022 images.

Do we know how to fix this?

[jeromelaban]

There are multiple possible reasons for this, but the main two are:

• The library does not contain a net6.0-ios TargetFramework, and the net6.0-ios app falls back to netstandard2.0
• The library does have a net6.0-ios16.1 target framework and app is built with a 6.0.100 SDK installed which is using a 15.4 SDK, causing the app to fall back to netstandard2.0 or similar (because 16.1 is higher than 15.4).

It is likely that you are in the second case, and if it is, you're likely building with the 7.0.100 SDK installed and you are then hitting dotnet/sdk#30103.

There's no fix for it at this time, and there are two known ways to workaround it:

• Build your library for net6.0-XXX only (and use a global.json to ensure that it is using a 6.0.XXX SDK), but that will prevent you from adding net7.0 using standard nuget packaging. Yet, it will allow for net6.0 apps built with a 6.0.XXX SDK to use the library.
• Build separately for net6.0-ios and net7.0-ios and aggregate the results manually with a nuspec file (very error prone and time consuming)

We assume that this will be fixed for .NET 8, but not convinced yet.

[jeromelaban]

I'm not seeing any failure in the binlog, what's the error you're seeing?

[jeanplevesque]

I have the same runtime error.
ObjCRuntime.RuntimeException: 'Can't register the class Nventive.ExtendedSplashScreen.ExtendedSplashScreen when the dynamic registrar has been linked away.'

[jeromelaban]

Your package is still building with the net7 SDK (see the 16.1 at the end):

It may be that running uno-check like in unoplatform/uno.toolkit.ui#488 will help forcing the SDK to be at the right version.

[jeanplevesque]

hmm that would mean that the global.json is not actually honored 😯

[jeromelaban]

It could very well be for workloads, workloads are troublesome. You can see in the binlogs that the proper SDK is used, but workloads are not.