UIView's shadowpath color doesn't change

Question

I have a UIView and I set a shadowPath for it like this:

func addShadow() {
    let cornerRadius: CGFloat = self.containerView.frame.height/2
    self.containerView.layer.shadowPath = UIBezierPath(roundedRect: self.containerView.frame, cornerRadius: cornerRadius).cgPath
    self.containerView.layer.shadowRadius = cornerRadius
    self.containerView.layer.shadowOffset = .zero
    self.containerView.layer.shadowOpacity = 0.2
    self.containerView.layer.cornerRadius = cornerRadius
    self.containerView.layer.shadowColor = UIColor(named: "whiteColor")?.cgColor
}

And this is whiteColor:

And now my problem is

When I change the appearance of the phone, the shadowPath's color doesn't change automatically. What should I do to make the color dynamic?

Answer 1

All layer properties don't react to color changes automatically (due to the conversion to CGColor).

Instead, react to trait collection changes and re-set the properties when the color appearance changes:

override open func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
    super.traitCollectionDidChange(previousTraitCollection)

    if #available(iOS 13, *), self.traitCollection.hasDifferentColorAppearance(comparedTo: previousTraitCollection) {
        // re-set your properties here
    }
}