MoveMe with layoutSubviews

MoveMeView.swift

import UIKit

struct Colors {
  static var normal = UIColor.blue
  static var selected = UIColor.red
}

extension CGPoint {
  static func add(_ left: CGPoint, _ right: CGPoint) -> CGPoint {
    return CGPoint(x: left.x + right.x, y: left.y + right.y)
  }
}


class MoveMeView: UIView {
  
  struct Model {
    var color = Colors.normal
    var scale: CGFloat
    var position = CGPoint.zero
  }
  
  private var model: Model! {
    didSet {
      // request layoutSubviews to be called again
      setNeedsLayout()
    }
  }
  
  private let cardView = UIView(frame: CGRect(origin: .zero, size: CGSize(width: 100, height: 100)))
  
  override init(frame: CGRect) {
    super.init(frame: frame)
    addSubview(cardView)
    backgroundColor = .lightGray
    let dragGesture = UIPanGestureRecognizer(target: self, action: #selector(onDrag))
    addGestureRecognizer(dragGesture)
  }
  
  required init?(coder: NSCoder) {
    fatalError()
  }
  
  override func layoutSubviews() {
    super.layoutSubviews()
    if model == nil {
      model = Model(color: .blue, scale: 1.0, position: center)
    }
    
    cardView.backgroundColor = model.color
    cardView.center = model.position
    cardView.transform = CGAffineTransform(scaleX: model.scale, y: model.scale)
  }
  
  @objc func onDrag(_ panGestureRecognizer: UIPanGestureRecognizer) {
    switch panGestureRecognizer.state {
    case .began:
      model.color = Colors.normal
      model.scale = 1.2
      UIView.animate(withDuration: 0.3, delay: 0, options: [.beginFromCurrentState]) {
        self.layoutIfNeeded()
      }
      

    case .changed:
      model.color = Colors.selected
      let translation = panGestureRecognizer.translation(in: self)
      model.position = CGPoint.add(translation, model.position)
      panGestureRecognizer.setTranslation(.zero, in: self)
      
    case .ended:
      model.color = Colors.normal
      model.scale = 1.0
      UIView.animate(withDuration: 0.3, delay: 0, options: [.beginFromCurrentState]) {
        self.layoutIfNeeded()
      }

    default:
      model.color = Colors.normal
    }
  }
}

ViewController.swift

import UIKit

class ViewController: UIViewController {
  
  lazy var movmeVw = MoveMeView(
    frame: CGRect(
      origin: .zero,
      size: CGSize(width: 100, height: 100)
    )
  )

  override func viewDidLoad() {
    super.viewDidLoad()
    view.addSubview(movmeVw)
  }
  
  override func viewDidLayoutSubviews() {
    super.viewDidLayoutSubviews()
    movmeVw.frame = view.frame
  }
}