Recently many people who updated Xcode to latest version 13.4 and trying to build project, they are facing the error: Undefined symbol: _OBJC_CLASS_$\
Undefined symbol: _OBJC_CLASS_$_xxx
Basically error Undefined symbol: _OBJC_CLASS_$ is seen when tried to update the Xcode version to the latest version 13.4 and try to run the project, it is throwing the error Undefined symbol: _OBJC_CLASS_$.
So as seen from the error, there are lot of library which are getting failed to load.
To fix the error Undefined symbol: _OBJC_CLASS_$, try to drag & drop the framework into Xcode, under the Frameworks group, once it is inline, it would fix the Undefined symbol: _OBJC_CLASS_$ error.
Alternatively, Make sure that the needed framework is included in the error files in your Link Binary with Libraries. Undefined symbol: _OBJC_CLASS_$ error will be fixed.
If nothing works for you, you can also try to clean library that remains unclean after adding / deleting some dependencies.
To clean libraries: Go to Xcode -> Product -> Clean Build Folder and rebuild the project. now it would fix the error Undefined symbol: _OBJC_CLASS_$ for you.
You can also visit to the Official release notes for XCode version 13.4 to check the known vulnerabilities and fixes provided by Apple developer team.