can i use the es3.1 api in code?
does ios supports opengl es3.x?
If I recall correctly, iOS supports ES 3.0 with a few extensions. So you may be able to get the 3.1 feature that you want by using ...EXT names. For example, separate_shader_objects.
What feature do you want from 3.1 ?
I used code shared by the windows developer, including some 3.x api such as glGetTexLevelParameter. I know little about opengl, not sure if it will work on iOS.
glGetTexLevelParameter
That doesn't seem to be available.