Zoom and pan an image in a scroll view with Auto Layout

ImageZoomAutolayout.swift

import UIKit

class ViewController: UIViewController {

  let scrollView = UIScrollView()
  let containerView = UIView()
  let imageView = UIImageView(image: UIImage(named: "quita"))

  override func viewDidLoad() {
    super.viewDidLoad()

    scrollView.translatesAutoresizingMaskIntoConstraints = false
    containerView.translatesAutoresizingMaskIntoConstraints = false

    scrollView.layer.borderWidth = 2.0
    scrollView.layer.borderColor = UIColor.blue.cgColor
    scrollView.delegate = self

    view.addSubview(scrollView)
    scrollView.addSubview(containerView)
    containerView.addSubview(imageView)

    NSLayoutConstraint.activate([
      scrollView.leadingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.leadingAnchor, constant: 20.0),
      scrollView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20.0),
      scrollView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -20.0),
      scrollView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -20.0),

      containerView.leadingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.leadingAnchor),
      containerView.topAnchor.constraint(equalTo: scrollView.contentLayoutGuide.topAnchor),
      containerView.trailingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.trailingAnchor),
      containerView.bottomAnchor.constraint(equalTo: scrollView.contentLayoutGuide.bottomAnchor),
      containerView.widthAnchor.constraint(equalTo: scrollView.frameLayoutGuide.widthAnchor),
      containerView.heightAnchor.constraint(equalTo: scrollView.frameLayoutGuide.heightAnchor),

      imageView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor),
      imageView.topAnchor.constraint(equalTo: containerView.topAnchor)
    ])
  }

  override func viewDidLayoutSubviews() {
    updateMinZoomScaleForSize(scrollView.frame.size)
  }

  func updateMinZoomScaleForSize(_ size: CGSize) {
    let widthScale = size.width / imageView.bounds.width
    let heightScale = size.height / imageView.bounds.height
    let minScale = min(widthScale, heightScale)

    scrollView.minimumZoomScale = minScale
    scrollView.zoomScale = minScale
  }
}

extension ViewController: UIScrollViewDelegate {
  func viewForZooming(in scrollView: UIScrollView) -> UIView? {
    return imageView
  }
}