How to animate borderColor change in swift

Question

For some reason this isn\'t working for me:

let color = CABasicAnimation(keyPath: \"borderColor\")
color.fromValue = sender.layer.borderColor;
color.toValue          


        

Answer 1

I created a Swift 4 function extension to CALayer for this, to which you can pass the starting and ending UIColors as well as the duration for the animation:

extension CALayer {

func animateBorderColor(from startColor: UIColor, to endColor: UIColor, withDuration duration: Double) {
    let colorAnimation = CABasicAnimation(keyPath: "borderColor")
    colorAnimation.fromValue = startColor.cgColor
    colorAnimation.toValue = endColor.cgColor
    colorAnimation.duration = duration
    self.borderColor = endColor.cgColor
    self.add(colorAnimation, forKey: "borderColor")
}

Note that for this to work, you should have already set a borderWidth and then call animateBorderColor:

yourView.layer.borderWidth = 1.5
yourView.layer.animateBorderColor(from: UIColor.green, to: UIColor.red, withDuration: 2.0)