As we said earlier, Metal is not the only option for you to work in 3D application or game. You have some other frameworks or third-party game engines, such as Unity or Unreal Engine. One of the built-in native frameworks is SceneKit. SceneKit is a very high-level engine that works with 3D models and worlds and can be used easily with SpriteKit. Both are high level, as we said, and don't give you any flexibility to work with low-level code or any access to GPU. For example, if you want to render a 3D model in SceneKit, it's just a piece of cake. But in Metal, it's not easy as it will take a lot of time and need a lot of code to be written. The trade-off is the full power and control while drawing this model. The other option is OpenGL ES, which is considered a great technology to work with 3D in iOS because of its high performance and the power it gives you during work - the same for its cross-platform. Metal gives you more power than OpenGL...