lifecycle.swift

import UIKit
import PlaygroundSupport

class MyViewControllerA : UIViewController {
  let viewControllerB = MyViewControllerB()

  override func loadView() {
    print("MyViewControllerA - loadView Invoked")
    let view = MyViewA()
    view.push = { [unowned self] in
      self.present(self.viewControllerB, animated: true, completion: nil)
    }
    self.view = view
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    print("MyViewControllerA - viewDidLoad Invoked")
  }

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    print("MyViewControllerA - viewWillAppear Invoked")
  }

  override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    print("MyViewControllerA - viewDidAppear Invoked")
  }

  override func viewWillDisappear(_ animated: Bool) {
    super.viewWillAppear(animated)
    print("MyViewControllerA - viewWillDisappear Invoked")
  }

  override func viewDidDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    print("MyViewControllerA - viewDidDisappear Invoked")
  }

}


class MyViewControllerB : UIViewController {
  override func loadView() {
    print("MyViewControllerB - loadView Invoked")
    let view = MyViewB()
    view.pop = { [unowned self] in
      self.dismiss(animated: true, completion: nil)
    }
    self.view = view
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    print("MyViewControllerB - viewDidLoad Invoked")
  }

  override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    print("MyViewControllerB - viewWillAppear Invoked")
  }

  override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    print("MyViewControllerB - viewDidAppear Invoked")
  }

  override func viewWillDisappear(_ animated: Bool) {
    super.viewWillAppear(animated)
    print("MyViewControllerB - viewWillDisappear Invoked")
  }

  override func viewDidDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    print("MyViewControllerB - viewDidDisappear Invoked")
  }

}

class MyViewA: UIView {
  typealias Interaction = () -> ()
  var push: Interaction?

  override init(frame: CGRect) {
    super.init(frame: frame)

    self.backgroundColor = .white

    let label = UILabel()
    label.frame = CGRect(x: 150, y: 200, width: 200, height: 20)
    label.text = "Hello World!"
    label.textColor = .black

    self.addSubview(label)

    let button = UIButton()
    button.setTitle("Push", for: .normal)
    button.setTitleColor(.systemBlue, for: .normal)
    button.frame = CGRect(x: 150, y: 275, width: 100, height: 20)
    self.addSubview(button)

    button.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchUpInside)
  }

  @objc func buttonTapped(_ sender: UIControl) {
    self.push?()
  }

  required init?(coder: NSCoder) {
    fatalError("We don't need this")
  }
}

class MyViewB: UIView {
  typealias Interaction = () -> ()
  var pop: Interaction?

  override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = .white

    let button = UIButton()
    button.setTitle("Close", for: .normal)
    button.setTitleColor(.systemBlue, for: .normal)
    button.frame = CGRect(x: 150, y: 275, width: 100, height: 20)
    self.addSubview(button)

    button.addTarget(self, action: #selector(buttonTapped(_:)), for: .touchUpInside)
  }

  @objc func buttonTapped(_ sender: UIControl) {
    self.pop?()
  }

  required init?(coder: NSCoder) {
    fatalError("We don't need this")
  }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewControllerA()