Anisotropic Shaders in SceneKit?

Is anyone aware of any work or has anyone ever written an anisotropic shader using glsl for SceneKit?

It's common place in renderers like Blender or Maya (can't link to the docs as the dev forums don't let me post urls, but it's easy to google).

Unity has anisotropic shader packages too, so it doesn't seem to be impossible to achieve in a game engine.