... book. Lines 2ff actually define the data used to describe the two cubes. You will rarely have to define anything in code like this. Usually, primitive shapes (spheres, cubes, and cones, for ... And it is not a pretty sight at times. Line 4 allocates an OpenGL context. This is used to keep track of all of our specific states, commands, and resources needed to actually render something ... lines of code to do only basic stuff. Besides making things easier to set up, the GLKView also handles the duties of calling your update and refresh routines and adds a handy snapshot feature...