That's really a lot of work, but it was fun to do (except some quirks here and here).
It's not possible to call directly objective C call as WinAPI, as it's not really calls, but messages. And the syntax doesn't fit regular API calls. The best for now is to do tiny C wrappers and use ImportC , that's how I did for the IDE and it works well. That said, wilbert wrote an objectiveC wrapper for PB to do some call:
http://www.purebasic.fr/english/viewtop ... bjective+C
About the flag, it's not planned for now, but it should be doable via a C call