How to animate layer shadowOpacity?

Question

I have a view on which I\'ve set the layerOpacity to 1.

    theView.layer.shadowOpacity = 1.0;

This looks fine when the view is farther down th

Answer 1

I've put above code in a little extension of UIView:

extension UIView {

func animateLayer(_ keyPath: WritableKeyPath, to value:Value, duration: CFTimeInterval) {

    let keyString = NSExpression(forKeyPath: keyPath).keyPath
    let animation = CABasicAnimation(keyPath: keyString)
    animation.fromValue = self.layer[keyPath: keyPath]
    animation.toValue = value
    animation.duration = duration
    self.layer.add(animation, forKey: animation.keyPath)
    var thelayer = layer
    thelayer[keyPath: keyPath] = value
}
}

Usage like:

animateLayer(\.shadowOffset, to: CGSize(width: 3, height: 3), duration:1)
animateLayer(\.shadowOpacity, to: 0.4, duration: 1)

It's not thoroughly tested. but worked for me. (Also posted here)