Pass by reference primitive types in Swift

Question

I am trying to have a model which shares a value with the objects it contains. In the below example I have a Model object, a, which contains a Struct , b. I would like them both to have access to a Bool which is referenced by variables a and aa. In order to do this, I have wrapped a Bool in a Box structure.

struct Box<Value> {
    var value:Value
}

struct Model {
    var a: Box<Bool>
    var b:B
    struct B {
        var aa:Box<Bool>
    }
}

struct TestView : View {
    @State var model:Model

    var body: some View {
        VStack {
            Text(model.a.value.description)
            Text(model.b.aa.value.description)

            Button(action: {
                self.model.a.value.toggle()
            }) {
                Text("Button")
            }
        }
    }
}

However, when I run the code as such:

let box = Box<Bool>(value: true)
let contentView = TestView(model: Model(a: box, b: Model.B(aa: box)))

The value in model.b.aa is not updated as I would expect. Is there a different way I should be doing this?

Answer 1

For your purpose, you'd need to wrap the primitive type in a class, and share an instance of that class. There is no raw reference or pointer that can be shared between the structs.