TouchAnimator_Stage1.swift

// Stage 1 simply moves the square's center point to the touch's location in self.view
// Tapping multiple times continues the same animation to the new point in the remaining animation duration

import UIKit
import SnapKit

class TouchAnimatorViewController: UIViewController {
  
  let animator = UIViewPropertyAnimator(duration: 2.0, curve: .easeInOut, animations: nil)
  let squareSize = CGSize(width: 100.0, height: 100.0)
  
  override func viewDidLoad() {
    super.viewDidLoad()
    
    setupViewHierarchy()
    configureConstraints()
  }
  
  private func configureConstraints() {
    darkBlueView.snp.makeConstraints{ view in
      view.center.equalToSuperview()
      view.size.equalTo(squareSize)
    }
  }
  
  private func setupViewHierarchy() {
    self.view.backgroundColor = .white
    self.view.isUserInteractionEnabled = true
    
    view.addSubview(darkBlueView)
  }
  
  
  internal func move(view: UIView, to point: CGPoint) {
    
    view.snp.remakeConstraints { (view) in
      view.center.equalTo(point)
      view.size.equalTo(squareSize)
    }
    
    animator.addAnimations {
      self.view.layoutIfNeeded()
    }
    
    animator.startAnimation()
    
  }
  
  
  override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else { return }
    move(view: darkBlueView, to: touch.location(in: view))
  }
  
  
  // MARK: - Views
  internal lazy var darkBlueView: UIView = {
    let view: UIView = UIView()
    view.backgroundColor = Colors.darkBlue
    return view
  }()
}