从目标C类调用C ++函数

Question

我想从目标C类中调用c ++函数，但不确定如何调用。请提供一些示例代码或有用的链接来帮助我，谢谢

Answer 1

将Objective-C文件上的.m扩展名更改为.mm以使其成为Objective-C ++ 。

Answer 2

An alternative to switching your class implementation file to Objective-C++ is to declare the C++ function as extern "C" , assuming its arguments are all C types. Place that declaration inside a C-compatible C++ header file and include it from both the C++ file that implements the function and from the Objective-C file that calls it. This will of course only work if the data types of parameters and the return type are pure C types, but is in some cases "cleaner" than the Objective-C++ approach.

Answer 3

Expanding on what pmjordan said, if you have a .m file calling in to a .mm or .cpp, make sure that the main header of the .mm or .cpp, where the functions you are calling are declared, have conditionally compiled extern "C" like this .h file:

#ifdef __cplusplus
extern "C" {
#endif

void functionA(void);
void functionB(const char *);

#ifdef __cplusplus
}
#endif

When this header is included as part of the .mm or .cpp, the extern "C" will do the right thing, and when the .h is compiled as part of the calling .c or .m file that calls those functions, the extern "c" is excluded and will not cause the compiler to complain.

Using this solution will prevent you from needlessly changing .m files into .mm files just so you can simply call C routines in c++ files.