In other frameworks, you will most probably have to import a physics engine library of your choice, such as Box2d, or chipmunk would configure it to make it work properly. You would also have to write custom code for making collision detection work. In SpriteKit, every scene has physics running in the background as soon as the scene is created. You are not required to do anything else to make it work. So, in the gameplay scene, we will disable the physics engine we created and replace it with SpriteKit's inbuilt physics engine.

Open up the gameplayScene.swift file and comment out the updateHero function in the update function. As you might remember, the updateHero function took care of making the hero get affected by gravity, making sure the hero was inside the screen at all times and also making sure thrust is applied when the player taps the left half of the screen. Using the inbuilt physics engine, we will see how we can make it do all the work for us.

As I said earlier, the physics...