A couple of weeks back I linked to John Nack's discussion of the 64-bit port of Photoshop, it's not a trivial task, but I'd forgotten you can mix C++ and Objective-C. This will make it easier for the Adobe crew to port Photoshop, but it's still going to be one heckuva chore!
Here's a VERY simple example. The Objective-C file, main in this case, is using the C++ class named CPPClass. Please note I had to rename the main.m file to main.mm so the compiler would treat it properly. I've also heard you can name the file '.M', or find a specific compiler setting that'll do the same trick for you. I don't know what that setting is, sorry.
Anywho, here's the simple sample.
int main(int argc, char *argv)
CPPClass* c = new CPPClass();
c->Method2("Rob was here");
return NSApplicationMain(argc, (const char **) argv);