I'm trying to create OpenGL 4.1 core context on Mac OS Yosimite (10.10.2) with SDL2.
But all I managed to get is 3.2 context with GLSL 150 (!). My GL initialization code looks like this:
Videocard: AMD Radeon HD 6750M 512 MB
I was going to add a comment but don't have enough reputation yet. I think you have likely not added the OpenGL framework to your project, or you could be including the wrong OpenGL .h file.
To add the framework: Go to your project settings, then Build Phases, then Link Binary with Libraries and then add the OpenGL framework.
What .h file are you using? I had problems creating a context with OpenGL.h but no problems with gl3.h