The preferred method of library distribution on OS X is through frameworks, and SDL is no different. Since SDL has several sub-libraries, each in a separate framework, the #include code is different between systems. (The OpenGL #include code is also different, for the record.)
#ifndef __APPLE__
#include <GL/gl.h>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include <SDL/SDL_mixer.h>
#elseif
#include <OpenGL/gl.h>
#include <SDL/SDL.h>
#include <SDL_image/SDL_image.h>
#include <SDL_mixer/SDL_mixer.h>
#endif
This is all fine and dandy but that actually gives me compilation errors in the frameworks' headers themselves, as they refer to files from other parts of SDL with the assumption they're in the same folder. One could edit the headers but other errors happen then. Since frameworks are the "proper" way of distributing libraries in your application bundles, I'm going to assume that there's just something wrong on my end and not that SDL frameworks are completely unusable by anyone.
In addition, a perturbing problem with OpenGL is that it insists that GLuint is not defined. This is baffling, considering you can go to OpenGL/gl.h yourself and plainly see the typedef of GLuint.
I've been struggling with these issues for a while and I'd appreciate it if someone would be able to help with this.