CODEWITHSUNDEEP
c++objective-cimportincludeobjective-c++
eonil
eonil

Reputation: 85955

How to import an [objective-c++] class which imports a [c++] class into an [objective-c] class?

I have 3 files.

// A.h/A.m, Objective-C.
#import "B.h"
@interface A
{
  B* b;
}
@end
// Uses instance method of B in implementation.



// B.h/B.mm, Objective-C++.
#import "C.h"
@interface B
{
  C c;  // c is declared without pointer.
}
@end
// Uses member methods of C in implementation.



// C.h/C.cpp, C++.
#include <Box2D/Box2D.h>  // C++ library.    
class   C
{
    private:
    b2World     world;
    b2Body*     ground;
    b2Body*     ball;

    public:

    PhysicsSimulator();
    ~PhysicsSimulator();

    void    setupWorld();
    void    cleanupWorld();

    void    tickWorld();
};
// One file of Box2D library include <cassert>

This makes compile-time error. 

/Users/eonil/Work/Trials/Box2DTest/Library/Box2D/Common/b2Settings.h:22:10: fatal error: 'cassert' file not found [1]

It looks I have to do something special when importing Objective-C++ from Objective-C. But I can't figure out what it is. And I'm not sure even that is possible or not. What's that..?

Upvotes: 1

Views: 1683

Answers (1)

Logan Capaldo
Logan Capaldo

Reputation: 40336

Don't include C.h in B.h. Rather say struct C;. This will allow you to forward declare the type in a way that is compatible with Objective-C. In the mm include C.h.

Upvotes: 4

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