Synchronously animate CALayer property and UIView with UIViewPropertyAnimator - ios

Question

I'm using a UIViewPropertyAnimator to animate the position of a view. But, I also want to animate CALayer properties like borderColor along with it. Currently, it doesn't animate and instantly changes at the start, like this:
Here's my code:
class ViewController: UIViewController {
var animator: UIViewPropertyAnimator?
let squareView = UIView(frame: CGRect(x: 0, y: 40, width: 80, height: 80))
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(squareView)
squareView.backgroundColor = UIColor.blue
squareView.layer.borderColor = UIColor.green.cgColor
squareView.layer.borderWidth = 6
animator = UIViewPropertyAnimator(duration: 2, curve: .easeOut, animations: {
self.squareView.frame.origin.x = 100
self.squareView.layer.borderColor = UIColor.red.cgColor
})
DispatchQueue.main.asyncAfter(deadline: .now() + 2) {
self.animator?.startAnimation()
}
}
}
I looked at this question, How to synchronously animate a UIView and a CALayer, and the answer suggested using "an explicit animation, like a basic animation." It said,
If the timing function and the duration of both animations are the same then they should stay aligned.
However, if I use CABasicAnimation, I lose all the benefits of UIViewPropertyAnimator, like timing and stopping in the middle. I will also need to keep track of both. Is there any way to animate CALayer properties with UIViewPropertyAnimator?

Answer 1

CABasicAnimation has timing as well as keyframe animation to stop in the middle. But, to replicate your animation above:
squareView.layer.transform = CATransform3DMakeTranslation(100, 0, 0)
let fromValue = squareView.transform
let toValue = 100
let translateAnimation = CABasicAnimation(keyPath: #keyPath(CALayer.transform))
translateAnimation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
translateAnimation.fromValue = fromValue
translateAnimation.toValue = toValue
translateAnimation.valueFunction = CAValueFunction(name: .translateX)
let fromColor = squareView.layer.borderColor
let toColor = UIColor.red.cgColor
let borderColorAnimation = CABasicAnimation(keyPath: "borderColor")
borderColorAnimation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
borderColorAnimation.fromValue = fromColor
borderColorAnimation.toValue = toColor
let groupAnimation = CAAnimationGroup()
groupAnimation.animations = [translateAnimation, borderColorAnimation]
groupAnimation.duration = 5
squareView.layer.add(groupAnimation, forKey: nil)