Question

I am experiencing either an extremely weird error or a temporary loss of brain function.

I have a box2d / cocos project running in XCode. This all works fine but my code is currently a proof of concept “hack”. Stage one of cleaning up the code is creating classes for various objects.

Now, if I create a brand new Objective C class (inherited off NSObject) as below it all compiles fine. As soon as I attempt to import the “Box2D.h” I receive a gazillion errors originating from the box2d library saying it cannot be built. 201 to be precise and it indicates no issues with the class itself. Can anyone shed any light? I have already tried a clean and rebuild as well as restarting XCode.

My super complicated class definition

#import "Box2D.h"

@interface test : NSObject

@end

An example compiler error thrown

Expected '=', ',', ';', 'asm' or '__attribute__' before 'b2Fixture' in /Users/..../libs/Box2D/Dynamics/b2Body.h

Answer 1

You need an Objective-C++ file for this, because Box2D is written in C++ and thus doesn’t compile in Objective-C out of the box. Luckily, its just a matter of renaming your file from myClass.m to myClass.mm