Question

i’m having some weird compiler errors in objective-c:

 iBody.h:18: error: ISO C++ forbids declaration of 'iObject' with no type

iObject.h

   #import "iElement.h"
   #import "CCSprite.h"
   #import "iBody.h"

   @interface iObject : iElement
   {
       iBody *body;
   }

    -(iObject*)initElement:(CGPoint)pos
          withName:(NSString*)name
            zIndex:(NSInteger)z
         withImage:(NSString*)image;

    -(void) addBody: (iBody*) body;
    -(iBody*) getBody;

 @end

iBody.h

  #import "iObject.h"
  #import "b2Body.h"

  @interface iBody : NSObject
  {
      CGPoint position;
      float angle;
      b2Body *body;
      iObject *parent;
   }

    -(iBody*) initElement: (CGPoint) pos
        withAngle: (float) angle
       withParent: (iObject*) el;

    -(void) setBody: (b2Body*)bdy;
    -(iObject*) getParent;

   @end

can someone please explain why this is happening and how to fix it. The implementation of the classes have .mm extension.

Thanks!

Answer 1

It seems like you’re in an import loop, since the headers of iBody and iObject are linking to one another. Typically in this situation I would consider the iObject to be of higher status and use the following in iBody.h:

// Replace the import to iObject.h with this:
@class iObject;

// Add the import back in iBody.mm
#import "iObject.h"

Now there is no import loop and only the implementation file of iBody actually links to iObject.h, and since no headers link to iBody.mm the issue is solved. Also, remember to rename the implementation files to .mm (Obj-C/C++) when working with Box2D, that gets me now and then 🙂