Hi, Fernando.
Thanks for your question—and welcome to the SpriteKit/GameplayKit party. 
To answer your question, yes. There are three chapters in this book that cover GameplayKit. The first one covers entities and components. The second one covers state machines, and the third one covers AI, including pathfinding with agents and behaviors. You’ll see these topics as you work on the second game in the book, Val’s Revenge.
Hope that helps!