struct ContentView: View {
    @State var count: Int = 3

    var body: some View {
        return NavigationView {
            VStack(spacing: 50) {
                HStack {
                    Button(action: { self.count += 1 }) {
                        Text("Add")
                    }

                    Button(action: { self.count -= 1 }) {
                        Text("Remove")
                    }
                }

                Circular {
                    ForEach(0..<max(0, count)) { i in
                        Color.green
                            .frame(width: 30, height: 30)
                            .clipShape(Circle())
                            .overlay(Text("\(i)").font(.headline).foregroundColor(.white).allowsTightening(true))
                            .shadow(radius: 3)
                    }
                }
            }.navigationBarTitle(Text("Full Circle"))
        }
    }
}

struct Circular<Items: View>: View {
    let items: [AnyView]
    let radius: Double = 100

    init<D, C0: View>(@ViewBuilder content: () -> Items) where Items == ForEach<D, C0> {
        let fe = content()
        self.items = fe.data.map { AnyView(fe.content($0.identifiedValue)) }
    }

    var body: some View {
        return ZStack {
            ForEach(0..<items.count) { idx in
                self.items[idx].modifier(self.positionModifier(at: idx))
            }
        }
        .background(Circle().foregroundColor(.gray).opacity(0.2))
        .frame(width: Length(2*radius), height: Length(2*radius))
        .animation(.fluidSpring())
    }

    func positionModifier(at index: Int) -> _PositionLayout {
        let r = (2*Double.pi / Double(items.count)) * Double(index)
        return _PositionLayout(position: CGPoint(x: sin(r)*radius+radius, y: cos(r)*radius+radius))
    }
}