True, however Apple's documentation suggested otherwise, that it was possible "with care".

But as you say, it never worked properly.

I think what you are referring to is "mixed mode" frameworks, which were able to work in both GC and RC environments. You had to do a bit of work to get that.

Which is similar but not quite the same thing. Mixing pure GC and pure RC frameworks was never possible. In fact, I think there were some flags and the (dynamic) linker would balk.