Hi I want to create an array of Views, each view has a button to append the array. Here is my code

struct ContentView: View {
    @State var views = [ButtonView]()

    let firstButton = ButtonView(id: 1, addView: { views.append(secondButton)})
    let secondButton = ButtonView(id: 2, addView: {})

    var body: some View {
        VStack {
            ForEach(views, id: \.id) { $0
            }
        }
        .onAppear{
            views.append(firstButton)
        }
    }
}

struct ButtonView: View {
    var id: Int
    let addView: () -> Void

    var body: some View {
        Button("Add View") {
            addView()
        }
    }
}

then I got the errors:

Cannot use instance member 'secondButton' within property initializer; property initializers run before 'self' is available

Cannot use instance member 'views' within property initializer; property initializers run before 'self' is available

I did search and didn't find anything related, then I asked chatGPT, chatGPT updated my code

struct ContentView: View {
    @State private var views = [ButtonView]()

    private lazy var firstButton = ButtonView(id: 1) { [weak self] in
        self?.views.append(self!.secondButton)
    }

    private let secondButton = ButtonView(id: 2) {}

    var body: some View {
        VStack {
            ForEach(views, id: \.id) { $0 }
        }
        .onAppear {
            views.append(firstButton)
        }
    }
}

struct ButtonView: View {
    let id: Int
    let addView: () -> Void

    var body: some View {
        Button("Add View") {
            addView()
        }
    }
}

Then I got another error Cannot use mutating getter on immutable value: 'self' is immutable on the line views.append(firstButton)

and ChatGPT never solve this error after several tries.

How to make it works? thank you if you could leave me some clue.

I would suggest not doing it like this.

Instead, do something like this:

struct ContentView: View {
    @State private var buttons: [ButtonData] = []

    var body: some View {
        VStack {
            ForEach(buttons) { button in
                Button("Add View") {
                    addButton()
                }
            }
        }
        .onAppear {
            buttons.append(ButtonData(id: 1))
        }
    }

    func addButton() {
        if let lastID = buttons.last?.id {
            buttons.append(ButtonData(id: lastID + 1))
        }
    }
}

struct ButtonData: Identifiable {
    let id: Int
}

Hi @roosterboy, thank you very much.

I choose to write that way, because I want to add different kind of View next, there will be diferent button to add different view.

Beyond that, I just want to know why I got the error Cannot use mutating getter on immutable value: 'self' is immutable what it means? what's fundamental law of it, or the deep knowlodge I missed.

And is it possible to make my code work, sorry I can't get rid of my OCD 😂

If you have a struct

struct Person {
    var name: String

    func makeAnonymous() {
        name = "Anonymous" // ERROR Cannot assign to property: 'self' is immutable
    }
}

so you have to tell it that that you changing it

struct Person {
    var name: String

    mutating func makeAnonymous() {
        name = "Anonymous"
    }
}

var person = Person(name: "Ed")

print(person) // prints Person(name: "Ed")

person.makeAnonymous()

print(person) // prints Person(name: "Anonymous")

Check out Mutating methods