如何在Xcode中使用宏检测c++编译器?

I'm mixing Objective-C (*.m) and Objective-C++ (*.mm) source files in an iOS project. When I import a C++ header file in a *.m file how can I exclude the C++-specific code in the header file? I want to use a compiler macro, something like:I'm mixing Objective-C (*.m) and Objective-C++