How to use @Observable to publish a class' properties

📚 Official Books Combine: Asynchronous Programming with Swift
1

I have tried to modify ColorCalc in chapter 19 to use @Observable for the CalculatorViewModel. There were several issues which I could not solve.

  1. Can no longer use @Published for properties.
  2. Cannot create publishers on properties by adding $
  3. Tried to use various solutions suggested, eg in stack overflow
    // See: swift - How to get a publisher from a value, since the beauty of @Observable? - Stack Overflow

@Observable
class Fool {
var cancellables = Set()

var isEnabled: Bool = false { didSet { isEnabled$ = isEnabled } }
@ObservationIgnored
@Published var isEnabled$: Bool = false

init() {
$isEnabled$
.removeDuplicates() // Prevent infinite loop
.sink { self.isEnabled = $0; print($0) }
.store(in: &cancellables)
}
}

However the above does not work in CalculatorViewModel, since in @Observables “didSet” is no longer called, though there is a complex solution apparently using withObservationTracking (eg see: Cancellable withObservationTracking in Swift – Augmented Code) which I could not get to work (newbie).

  1. It seems easier to just implement computed variables for all model properties that depend upon hexText, eg
    var color: Color {
    if let c = Color.redGreenBlueOpacity(forHex: hexText) {
    return Color(values: c)
    }
    return .white
    }
    var rgboText: String {
    if let values = Color.redGreenBlueOpacity(forHex: hexText) {
    return [values.0, values.1, values.2, values.3]
    .map { String(describing: Int($0 * 255)) }
    .joined(separator: ", ")
    }
    return “—, —, —, —”
    }
    var name: String {
    let name = ColorName(hex: hexText)
    if let name {
    return “(name) (Color.opacityString(forHex: hexText))”
    } else {
    return “------------”
    }
    }

  2. So my main question is, do I have to continue to use ObservableObject with @Published rather than move to the “modern” @Observable. Apple have stated we can just swap this for our ObservableObjects and it all should just work, but it doesn’t with Combine (as far as I can tell).
    Thoughts from the experts please?