ObservedObjectAndStateObject.swift

import SwiftUI

class Counter: ObservableObject {
  @Published var count: Int
  
  init(_ count: Int) {
    self.count = count
  }
  
  func increment() {
    count = count + 1
  }
}

struct CounterView: View {
  
  @ObservedObject var counter: Counter
  
  var body: some View {
    Text(String(counter.count))
    Button("+ 1", action: { counter.increment() })
  }
}


struct ContentView: View {
  
  @StateObject var counter = Counter(0)
  @State var random: Int = 0
  
  var body: some View {
    VStack {
      CounterView(counter: counter)
      
      Spacer()
      
      Text(String(random))
      Button("Random", action: { random = Int.random(in: 1...10) })
    }.font(.system(size: 26))
  }
}