Objective C with some C++ code won't compile

Question

I have an Objective C project with some C++ code, and sure enough the C++ code won't compile

I understand that the compiler makes assumptions about which language to compile, but I have seen this app running before so I am curious how to make my Xcode 4 run compile this project

ie. This function declaration produces an error as the compiler does not recognize the c++ std:: syntax

 std::string string_with_formatting(const unsigned int value)
 {

How do I get around this? What #include or #import should I have

Answer 1

Objective-C++ is a superset of C++. You can use C++ in Objective-C++ sources.

1. Make sure the file has .mm extension, otherwise it will be treated as Obj-C, not Obj-C++
2. #include <string>