SwiftUI Challenge

ContentView.swift

/**********
  YOUR CHALLENGE, SHOULD YOU CHOOSE TO ACCEPT IT:
      Modify the code below to work with a list
      of arbitrary size *without* preallocating a
      fixed-length array.

  REPLY @braddwyer ON TWITTER WITH YOUR SOLUTION HERE:
  https://twitter.com/braddwyer/status/1141744658399334401

  (Original challenge via @JadenGeller, https://twitter.com/JadenGeller/status/1141300214654881792 )
**********/

//
//  ContentView.swift
//  SwiftUI Challenge Accepted
//
//  Created by Brad Dwyer on 6/19/19.
//  Copyright © 2019 Brad Dwyer. All rights reserved.
//

import SwiftUI
import Combine

struct ContentView: View {
    var nums:[Int] = []
    
    // HACK: set `count` to the maximum number of list items you want to support!
    @State var counts:[Int] = [Int].init(repeating: 0, count: 100)
    
    init() {
        self.init(data:[1,2,3,4,5])
    }
    init(data:[Int]) {
        self.nums = data
    }
    
    var count:Int {
        get {
            var ret = 0
            for v in counts {
                ret = ret + v
            }
            return ret
        }
    }
    
    var views:[ToggleView] = []
    var body: some View {
        return VStack {
            NavigationView {
                List {
                    ForEach(nums.indices) { i in
                        ToggleView(i: i, nums: self.nums, counts: self.$counts)
                    }
                    }
                    .navigationBarTitle(Text("My favorite numbers!"))
            }
            Text("The sum of my favorite numbers is \(count).").padding()
        }
    }
}

struct ToggleView : View {
    var i:Int
    @State var nums:[Int]
    @State var on:Bool = false
    @Binding var counts:[Int]
    
    var isOn:String {
        get {
            if(self.on) {
                self.counts[self.i] = self.nums[self.i]
            } else {
                self.counts[self.i] = 0
            }
            
            return self.on ? "on" : "off"
        }
    }
    
    var body: some View {
        return Toggle(isOn: $on) {
            Text("I like the number \(nums[i]) \(isOn)")
        }
    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView(data: [1,2,3,4,5,6,7,8,9,10])
    }
}
#endif