In this chapter, we talked about the new graphics framework Metal and its features. We gave a simple introduction to 3D rendering and how it works in programming and how computers deal with it. We used the project template that came with Xcode in Metal to draw a moving triangle in 3D space and tried to explain all major areas in code, such as devices, shaders, pipeline, command queue, command buffer, and game loops. In the next chapter, we will cover a very interesting topic, which is WatchKit development. You will learn how to start your Apple watch app development in Xcode and what you can deliver to the users in watch app.