SDL2 for the Nintendo Wii U (build with "cmake [SDL source path] -DCMAKE_TOOLCHAIN_FILE=$WUT_ROOT/share/wut.toolchain.cmake -DCMAKE_INSTALL_PREFIX=$DEVKITPRO/portlibs/wiiu")
When SDL is included as a subproject, the following error might appear:
```
CMake Error: Error required internal CMake variable not set, cmake may not be built correctly.
Missing variable is:
CMAKE_OBJC_COMPILE_OBJECT
```
This is probably because the master project does not see certain OBJC related variables
Simple DirectMedia Layer is a cross-platform development library designed
to provide low level access to audio, keyboard, mouse, joystick, and graphics
hardware via OpenGL and Direct3D. It is used by video playback software,
emulators, and popular games including Valve's award winning catalog
and many Humble Bundle games.
More extensive documentation is available in the docs directory, starting
with README.md