UIView, shadow

UIView.swift

// dropsahdow
extension UIView{
    func dropShadow(shadowColor: UIColor = UIColor.black,
                    fillColor: UIColor = UIColor.white,
                    opacity: Float = 0.2,
                    offset: CGSize = CGSize(width: 0.0, height: 1.0),
                    radius: CGFloat = 10) -> CAShapeLayer {

        let shadowLayer = CAShapeLayer()
        shadowLayer.path = UIBezierPath(roundedRect: self.bounds, cornerRadius: radius).cgPath
        shadowLayer.fillColor = fillColor.cgColor
        shadowLayer.shadowColor = shadowColor.cgColor
        shadowLayer.shadowPath = shadowLayer.path
        shadowLayer.shadowOffset = offset
        shadowLayer.shadowOpacity = opacity
        shadowLayer.shadowRadius = radius
        layer.insertSublayer(shadowLayer, at: 0)
        return shadowLayer
    }
}