How can I animate a gradient layer which increases its width? - swift

Question

I'm using a simple UIView which I want to animate and I added a gradient layer to it.
I want to increase the width of the view and the layer placed on the view,
but all I get is that the view increases its width but not the layer.
Example: Let's say I have a UIView with height = width = 50
I animate it by setting the width to: width += 50. This animation is working. If I do the same with layer then noting happens. The layer does not increase its width. I tried some things to fix this (see comments in code) but nothing is working.
Here is my code
func performNextTitleAnimation() {
let overlayViewHeight = overlayView.frame.size.height
let overlayViewWidth = overlayView.frame.size.width
let animationHeight: CGFloat = 48
let overlayViewHalfHeight = (overlayViewHeight) / 2
swipeAnimation = UIView(frame: CGRect(x: 0, y: overlayViewHalfHeight - (animationHeight/2), width: 48, height: animationHeight))
swipeAnimation.backgroundColor = .gray
swipeAnimation.layer.cornerRadius = swipeAnimation.frame.size.height / 2
gradientLayer.frame = swipeAnimation.bounds
overlayView.addSubview(swipeAnimation)
swipeAnimation.layer.addSublayer(gradientLayer)
UIView.animate(withDuration: 1.2, delay: 0, options: [.repeat], animations: {
self.gradientLayer.cornerRadius = 24
self.swipeAnimation.frame.size.width += 50
//Things I tried, but not working
//1.) self.gradientLayer.frame.size.width += 50
//2.) self.gradientLayer.frame.size.width = self.swipeAnimation.frame.size.width
//3.) self.gradientLayer.bounds = self.swipeAnimation.bounds
}, completion: nil)
}
Gradient Layer
gradientLayer.colors = [UIColor.white.cgColor, animationColor.cgColor]
gradientLayer.locations = [0.0, 1.0]
gradientLayer.transform = CATransform3DMakeRotation(3*(CGFloat.pi) / 2, 0, 0, 1)
Any help is highly appreciated.

Answer 1

The best result I've ever achieved when I needed to animate CAGrandientLayers size is to use it as a layerClass of a custom UIView:
class GrandientView: UIView {
override class var layerClass : AnyClass {
return CAGradientLayer.self
}
var gradientLayer: CAGradientLayer {
// it is safe to force cast here
// since we told UIView to use this exact type
return self.layer as! CAGradientLayer
}
override init(frame: CGRect) {
super.init(frame: frame)
// setup your gradient
}
}