After reading through the source code of chapter 5, I feel that the challenge needs more hint for people to do it by themselves.
It is a bit difficult to know what ViewValues does, and how to use it without any additional hints. Maybe add some comments about how ViewValues should be used would be more helpful.
Also there has been some git conflicts that leaked into the master branch, SceneDelegate.swift of the challenge section of chapter 5. I have created a pull request to address that issue.