i'm not Quinn, but I'd say what I think. The expression is a closure passed in the set: parameter of the initialiser. You need to pass a closure that takes a newValue parameter (of the T type as in Binding, which here is Bool) as input, and set it to whatever other variable you use. You use another variable to store the binding's actual value, and this value is of type MyBool.

Thanks! I reviewed the options, and I was wondering which run destination (not target, sorry) will be used when choosing the Xcode option. I was worried about an issue I had with a SwiftUI NavigationSplitView in Mac Catalyst (FB12108868), but I found a workaround and I don't think I'll have any specific instructions.

Make sure to check if your app builds and runs on Swift Playgrounds.

NavigationView is deprecated. You can use NavigationStack and NavigationSplitView instead. Here you can find more details.