Undefined symbol "_OBJC_CLASS_$_GCController" error on Mac

[TheMostDiligent]

Version/Branch of Dear ImGui:

Version: 1.89.1 Branch: master

Back-end/Renderer/Compiler/OS

Back-ends: imgui_impl_osx.mm + custom Compiler: AppleClang 13.1.6.13160021 (XCode 13.4) Operating System: MacOS (M1, arm64)

My Issue/Question:

After updating to the latest version (my was ~3 years old), I started getting the following linking errors when building on MacOS:

Undefined symbols for architecture arm64:
  "_OBJC_CLASS_$_GCController", referenced from:
      objc-class-ref in libDiligent-Imgui.a(imgui_impl_osx.o)
ld: symbol(s) not found for architecture arm64

There seems to be nothing special about how imgui_impl_osx.mm is being built compared to other objective-c++ files, and I ran out of ideas of what may be wrong. Googling "_OBJCCLASS$_GCController" gives exactly zero relevant results. I tried:

• Building with ARC on and off (the entire project is built with ARC off), which made no difference
• Add some frameworks (Coca, CoreFoundation, etc.), which also did not make any difference

Any suggestion would be highly appreciated. Thank you!

[TheMostDiligent]

OK, after comparing the example XCode project settings line-by-line I finally found that Mac implementation now requires the GameController framework. Linking with it fixed the problem. It may be worth adding a note in imgui_impl_osx.mm that this framework is now a requirement.

[ocornut]

Thank you, will add comments in an incoming commit.