The next big topic that we will discover is physics in our application. Physics-based games are very popular on the App Store. Angry Birds, Tiny Wings, and Cut the Rope are all physics-based. They offer lifelike interactions that are fun and appealing.
Another reason why we might want to have a physics engine is that it offers a lot of functionality "for free". You no longer need to calculate different complicated collisions, forces, and all things that may affect your nodes. Most of these things are handled for you by a physics engine.
Physics simulation basics
If you want your node to participate in physics simulation, you have to add a physics body to it. There are many available methods to generate physics bodies, and they are ...