Congrats on getting this far. If this book were a game, we'd probably have earned an achievement for this chapter alone. As we saw, working with a low-level API such as Metal can be a bit daunting. We first reviewed what it means when developers and engineers mention lower and upper level frameworks and code. On the CPU side, we saw that the lowest level is the machine's code with Swift and Objective-C in the middle, and above C/C++ and Assembly code. Next, we spoke about the GPU side and where the visual graphics APIs we've gone over in the past chapters stand in the hierarchy. We then got an understanding of the history of lower-level graphics APIs such as OpenGL ES, how the graphic pipeline generally works under the hood, and how to make basic shaders. Finally, we reviewed why Metal is faster during the render cycle than OpenGL, the general structure behind Metal, and some of the code/objects used to manually set up the render loop. This chapter merely scratched the surface on...