Strange bug
if build using cmake/cmake
mkdir build
cd build
cmake ..
make
the resulting code can't render, because the MyMTKViewDelegate::drawInMTKView function never gets called.
if build using cmake/xcode
mkdir build
cd build
cmake .. -G Xcode
# open the xcode project and run
the resulting code can render fine. However, if the binary is launched from the terminal, it won't render either.