Unity version: 2021.3.4f1
Device: not relevant for this error
Just saying, I took over the project, so am not 1000% familiar with it.
We were using Unity 2020.3.18f1 just until yesterday and I now wanted to try an upgrade (no worries, backups etc. are available) to the latest Unity LTS version. When building the project for iOS inside Unity, there are no problems, but when building in XCode, the following error message occurs:
Undefined symbols for architecture arm64: "_OBJC_CLASS_$_EAGLContest", referenced from: objc-class-ref in libUnityiOSBridge.a(libUnityiOSBridge.a-arm64-master.o) ld: symbol(s) not found for architecture arm64
This error did not happen in Unity 2020.3.18f1, so I am a bit left confused as to why this happens now, even though the release notes of the 9.8.0 SDK mention fixing build issues related to OpenGLES.
I can fix this error by manually adding OpenGLES.framework in my XCode projects' Libraries and Framework section, but would of course prefer if it can be solved more easily.
If anyone has any idea of what the cause of this might be, please let me know.
I just realised that we are using the Expert edition (checked via "View Changelog" in the Unity package manager), so the fix for 9.8.0 SDK does not apply here, because this is only for the Professional edition.
The issue is fixed by checking the OpenGLES checkbox of the Packages/com.wikitude.core/Runtime/Plugins/iOS/libUnityiOSBridge.a plugin. See https://forum.unity.com/threads/unity-2021-lts-is-now-available.1263407/page-5#post-8206773 for more information.