Adding this in case anyone else has had similar issues…
Following the instructions in the 8th edition of iOS Apprentice, chapter 11, page 364, I used “refactor” to rename the ContentView to ChecklistView.
For some reason, that went terribly wrong, and nothing worked for a while. I then had to manually rename the ContentView.swift file in the finder, and then had to go through the code and manually rename instances of “contentView” or “ContentView” with “checklistView” or “ChecklistView.”
After renaming things manually, all seems to be working. But I wonder if the refactor tool in XCode doesn’t really work as expected.