you're on the right track. The compiler reports missing symbols, so you need to add the implementation file with those missing things.
SWELL_CStringToCFString is in swell-misc.mm
https://github.com/justinfrankel/WDL...ll-misc.mm#L87
If you don't compile that with your code you'll get an error.
BUT - if you are trying to do something with modstub, you have to link against swell.dylib, rather than compiling swell-misc.mm etc with your project
https://github.com/justinfrankel/WDL...modstub.mm#L29