GLKVector2 doesn't have 'r' or 'g' components, unlike the longer vector types, and GLKQuaternion has 'x', 'y', 'z', and 'w' components. Thanks Jordan for pointing these out.
Swift SVN r23895
We can access pretty much all of the GLKit functions now, but still lacked accessors for the individual elements. gyb up some accessors to do dirty bitcasting tricks to expose the elements of GLKVectorN, GLKMatrixN, and GLKQuaternion values.
Swift SVN r23892