FavoriteNumber SwiftUI.swift

struct FavoriteNumber {
    var number: Int
    var isFavorite: Bool

    init(_ number: Int) {
        self.number = number
        isFavorite = false
    }
}
struct ContentView : View {
    @State var numbers = (1...10).map(FavoriteNumber.init)
    var body: some View {
        NavigationView {
            VStack {
                List($numbers.identified(by: \.value.number)) { num in
                    Toggle(isOn: num.isFavorite) {
                        Text("I like the number \(num.value.number)")
                    }
                }
                Text("The sum of my favorite numbers is \(sum)")
                    .padding()
            }
            .navigationBarTitle(Text("My favorite numbers!"))
        }
    }

    var sum: Int { numbers.filter { $0.isFavorite }.reduce(0) { $0 + $1.number } }
}