混合Objective - C,(*。m *。mm & c /。cpp)文件

In my project Core libraries are part of C/C++ files, while UI needs to be developed in Objective C, I am able to access/Call C++ functions from Objective C/.mm files but reverse no luck so far, i.e. i am not able to call Objective C functions from C++ Files, when i tried to include Objective C header even system header In my project Core libraries are part of C/C++