BindingObservedObject.swift

//: A UIKit based Playground for presenting user interface

import SwiftUI
import UIKit
import PlaygroundSupport

class Model: ObservableObject {
  @Published var on: Bool = false
}

class Thing: NSObject {

  @ObservedObject var model = Model()

}

var thing = Thing()

struct MyView: View {

  @Binding var on: Bool

  var body: some View {
    Rectangle()
      .foregroundColor(on ? .blue : .red)
      .frame(width: 100.0, height: 100.0, alignment: .center)
      .onTapGesture {
        self.on.toggle()
        print(self.on)
    }
  }

}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = UIHostingController<MyView>(rootView: MyView(on: thing.$model.on))