W6D2-Keyframe-Animation

W6D2-Keyframe-Animation.swift

import PlaygroundSupport
import UIKit

class MyVC: UIViewController {
  let button = UIButton()
  override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .red
    view.addSubview(button)
    button.setTitle("button", for: .normal)
    button.addTarget(self, action: #selector(animateKeyFrames), for: .touchUpInside)
    button.isEnabled = true
    button.sizeToFit()
  }
  
  override func viewDidLayoutSubviews() {
    button.center = view.center
  }
  
  @objc func animateKeyFrames() {
    UIView.animateKeyframes(withDuration: 2.0, delay: 0, animations: {
      UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.25, animations: {
        self.button.transform = CGAffineTransform(rotationAngle: 0.5*CGFloat.pi)
      })
      UIView.addKeyframe(withRelativeStartTime: 0.25, relativeDuration: 0.25, animations: {
        self.button.transform = CGAffineTransform(rotationAngle: CGFloat.pi)
      })
      UIView.addKeyframe(withRelativeStartTime: 0.5, relativeDuration: 0.25, animations: {
        self.button.transform = CGAffineTransform(rotationAngle: 1.5*CGFloat.pi)
      })
      UIView.addKeyframe(withRelativeStartTime: 0.75, relativeDuration: 0.25, animations: {
        self.button.transform = CGAffineTransform(rotationAngle: 2*CGFloat.pi)
      })
    })
  }
}

let vc = MyVC()
PlaygroundPage.current.liveView = vc
PlaygroundPage.current.needsIndefiniteExecution = true