Im trying to use properties of @State var and @Binding var variables in the initialization process of my View but I don’t really understand if the way im doing it is a conventional or “legit” way of doing it or if it’s just that i can’t do it the “legit” way because i dont understand how @State var and @Binding var works.

This is what im currently doing

struct EditPrView: View {

    @State var name: String
    @State var nameCount: Int = 0 // Some value just to initalise the variable

    var body: some View {
        VStack {
            Text(name)
            Text(String(nameCount))
        }.onAppear(perform: { // Do the "actual" assigment here
            nameCount = name.count
        })
    }
}

This works well (i havent run in to issues yet) but it feels “hacky” and i feel like this should be able to be done in the initialization phase of the view.

This is what i have tried

struct EditPrView: View {

    @State var name: String
    @State var nameCount: Int = name.count // This will throw an error

    var body: some View {
        VStack {
            Text(name)
            Text(String(nameCount))
        }
    }
}

This obviously doesn’t work and you get a compile time error immediately

class A {
    var a: Int = 0
}

class B: A {
    var b: Int = 5
}

struct EditPrView: View {

    @State private var obj: A?
    @State private var count: Int

    init(obj: A?) {
        self.obj = obj
        if obj is B {
            self.count = 2
        } else {
            self.count = 1
        }
    }

    var body: some View {
        VStack {
            Text("foo-bar")
            Text(String(count))
        }
    }
}

#Preview {
    var b: A? = B()
    return EditPrView(obj: b)
}

This works fine while im only using @State in a view

class A {
    var a: Int = 0
}

class B: A {
    var b: Int = 5
}

struct EditPrView: View {

    @Binding private var obj: A?
    @State private var count: Int

    init(obj: Binding<A?>) {
        self._obj = obj
        self.count = 0
        if self.obj is B {
            self.count = 2
        } else {
            self.count = 1
        }
    }

    var body: some View {
        VStack {
            Text("foo-bar")
            Text(String(count))
        }
    }
}

#Preview {
    @State var b: A? = B()
    return EditPrView(obj: $b)
}

But then i try to add a @Binding var like this and it’s like it doesnt even get to the else statement, it just sets self.count to 0 and then continues makes the view appear even if the instance clearly is of type B.

Since i want one way of doing view initialization this has made me stick to the .onAppear(perform: ) way of initalizing variables but as the question asks, is this really the way to do it?

TLDR

Why doesnt the if statement in the last code-block example fire?