Feedback: SwiftUI's Observable macro is not a drop-in replacement for ObservableObject

[malhal]

Using @State at the app level causes the object to be init too soon so should be avoided. E.g. it'll be init during Previews even when App's body isnt called.

Better fix is just to conform your class also to ObservableObject then you can continue to use it with @StateObject. So think of @Observable as an alternative just for @Published.

[jessesquires]

Thanks @malhal !

Yes, in some scenarios, you might have to continue using ObservableObject. It certainly depends on the context and use case. 😊

[malhal]

Yes you're right, e.g. for a top level model object, you can do a fileprivate letoutside of the app struct. In Swift globals are lazy and if you use it from body then that gives the same semantics as StateObject without needing ObservableObject for your @Observableclass, e.g.

fileprivate let model = Model() // @Observable class

struct App: App {
   var body: some Scene
       ...
       .environment(model) // model is init here once.
   }
}

Downside is the model can't be re-init.