I've been working my way through the online version of the book right now - I'm finishing up Project 14 BucketList. I have to say I am so impressed with this book/tutorial. I've previously watched all the WWDC SwiftUI videos, done lots of poking around various places and learning things here and there. It came time to start actually building out an app using SwiftUI and even with what felt like a lot of (somewhat undirected) research, I found myself quickly in over my head - spending lots of time moving things around without really understanding what or why.
I then started this online tutorial (book) and can't be more happy that I did. It starts very slow and continually builds - taking you through not just what to do, but most importantly how things work under the hood and why you might want to do things certain ways. Incredibly helpful. I had spent a couple weeks building out a basic app and kept running into data flow problems. After I read through the Core Data bits (Project 11 and 12) I went back and in a couple days had rewritten what I had done and now have the basic flow correct.
I've been writing Swift for a couple years and this book really benefits from having comfort with Swift and your environment. I spent a couple years using UIKit and that definitely helps as well since wrapping UIKit frameworks will need to be done.
I very much recommend going through this book even if it's a year out of date. SwiftUI isn't really changing , it's growing. So what's in here is very valid and I have not seen one place where the code didn't compile because things have changed. I had no idea MapKit integrates more thoroughly with SwiftUI until I read this thread, but learning how to bridge it in will allow me to bridge things like UICloudSharingController and other pieces that I will specifically need.
You won't regret going through this book. I'm at Project 15 now and the only things that aren't correct are the ones that you bring up (Single View App and AppDelegate/SceneDelegate).
