Yes, it's true that ObjC is pretty firmly entrenched after so many years driving the platforms. But it also doesn't feel like I'm doing myself many favors professionally by investing any further time into that language. For personal stuff, I can do whatever of course. I dunno, maybe I'm wrong; can't say I've researched "How in-demand are ObjC skills in the job market?" these days to speak with any authority on the matter.

and neither is OpenGL