How to update a single child view in SwiftUI?

Question

I am trying to establish a SwiftUI connection between the child view and the parent view. By clicking on any child view, I want to redraw only the view that has been tapped, not

Answer 1

I think I've found a solution. The first problem was that I initialized array of colors by repeating the same element instead of adding independent ones.

What is more CustomColor itself should have BindableObject conformance, not the model (we don't change the array of colors, we change each color). Lastly, we don't need to wrap objects in ForEach element (we loose reusability that way), and instead we put them in List element.

With this implementation, only the view that has been changed will be redrawn, not the entire collection.

Here is the code:

class CustomColor: BindableObject, Identifiable {

    var didChange = PassthroughSubject()

    let id = UUID()
    var color: Color {
        didSet {
            self.didChange.send(self)
        }
    }

    init(color: Color) {
        self.color = color
    }

    func change(toColor color: Color) {
        self.color = color
    }

}

class ColorStore {

    var colors: [CustomColor] = []

    init() {
        (0...10).forEach { _ in colors.append(CustomColor(color: .red)) }
    }

}


struct ContentView: View {

    let colorStore: ColorStore

    var body: some View {
        NavigationView {
            List(colorStore.colors) { color in
                ColorShape(color: color)
            }.navigationBarTitle(Text("Colors"))
        }
    }

}

struct ColorShape: View {

    @ObjectBinding var color: CustomColor

    var body: some View {
        Button(action: { self.color.change(toColor: .blue) }, label: {
            ShapeView(shape: Circle(), style: color.color)
        })
    }

}