I am using Learn to Code 2, and have finished all the exercises through Reach for the Stairs, and all was fine. When I started the next exercise, Floating Islands, all of the movement methods such as isBlocked, moveForward, etc. have gone away. I can place blocks, stairs and portals as I wish, but that's it. If I type "if " the suggestions such as isBlocked are not shown. I've quit and restarted the Playgrounds app, restarted the computer, and ran Onyx and re-started again to no effect. The previous exercise still runs fine. What am I missing?

I'm trying to go through the exercises in "Develop in Swift Fundamentals", 12/27/2020, but the exercises aren't compatible with the three versions of Xcode I've tried. For example, on page 79, the instructions are to “In ViewController.swift, add the following lines of code below super.viewDidLoad():" But super.viewDidLoad () isn't to be found in the contents area. I started with the latest version of Xcode, 12.7. Then I noticed that the book was using a version 11 of Xcode, so I tried versions 11.7 and 11.2.1, but they weren't compatible either. Can someone tell me what version of Xcode is compatible with the book I'm using? Thank you