UIButton bottom shadow

Question

I have a UIButton which is very similar to the standard iOS keyboard alphabet button.

I am not sure how to create a shadow only for the bottom layer li

Answer 1

To add shadow to a button with corner radius:

final class CustomButton: UIButton {

    private var shadowLayer: CAShapeLayer!

    override func layoutSubviews() {
        super.layoutSubviews()

        if shadowLayer == nil {
            shadowLayer = CAShapeLayer()
            shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: 33).cgPath
            if self.backgroundColor != nil {
                shadowLayer.fillColor = self.backgroundColor?.cgColor
            }
            else{
                shadowLayer.fillColor = UIColor.white.cgColor
            }
            shadowLayer.shadowColor = UIColor.gray.cgColor
            shadowLayer.shadowPath = shadowLayer.path
            shadowLayer.shadowOffset = CGSize(width: 0.0, height: 3.0)
            shadowLayer.shadowOpacity = 0.4
            shadowLayer.shadowRadius = 2

            layer.insertSublayer(shadowLayer, at: 0)

        }

    }

}