Hey, Developer Tools Engineer, Julia is an excellent presenter! If you see her, could you please correct her pronunciation of "model"? She makes it sound like "modal", which was a bit distracting. And give her a thumbs up for her good teaching style.

I did see that, but I don't automatically have a good idea of what it means. I'm used to declarative UI libraries like Cocoa and Delphi, where the views would be represented by objects of a class, and have a property "label" or "text" or whatever. The code for confirmation dialog could read that, but in SwiftUI, as we have here, the Button is a black box, so it is not clear how it can read the label string. It's a hidden requirement. Grrrr. I hate those.

I am on Xcode 14.3, the app is now called "Simulator", the top-level menu option is now I/O, but whether Connect Hardware Keyboard is on or not, I get the Keyplane error. It is incumbent on Apple to fix this. I prefer my output pane to be clean.

You asked "Where does the for loop mutate threeToGo?" The for loop will have to call threeToGo.next(), which is a mutating func. func next() is the declaration required by IteratorProtocol to allow it to provide the values in a for loop.

The question is: Why does a let work in the for loop? It is still having to call next(). That is what makes it IteratorProtocol, and thus allowed to be used in a for loop.

That is right. I was thinking the code in the for loop would also regard the expression after "for i in" as a let value.

But there you are adding a new Back button. I see that as a Cancel button. I wanted to insert an alert to say "Changes will be lost if you quit without saving Quit | Stay", or something like that. I am thinking I will avoid using the default NavigationLink behaviour and add my own buttons, as you are suggesting.

I don't know about that one.

I tried this out more recently and it works now.