Views with simple effects

RoundedView.swift

@IBDesignable class GradientView: RoundedView {
    @IBInspectable var topColor:UIColor = .clear { didSet { setNeedsLayout() } }
    @IBInspectable var bottomColor:UIColor = .black { didSet { setNeedsLayout() } }

    override func layoutSubviews() {
        super.layoutSubviews()

        let gradient: CAGradientLayer = CAGradientLayer()
        gradient.frame = bounds
        gradient.colors = [topColor.cgColor, bottomColor.cgColor]
        layer.insertSublayer(gradient, at: 0)
        isOpaque = false
        backgroundColor = .clear
    }
}

@IBDesignable class RoundedView: UIView {
    @IBInspectable var isRelativeRadius:Bool = true { didSet { setNeedsLayout() } }
    @IBInspectable var cornerRadius:CGFloat = 0.5  { didSet { setNeedsLayout() } }
    @IBInspectable var borderWidth:CGFloat = 0  { didSet { setNeedsLayout() } }
    @IBInspectable var borderColor:UIColor = .clear  { didSet { setNeedsLayout() } }

    override func layoutSubviews() {
        super.layoutSubviews()

        layer.masksToBounds = true
        layer.cornerRadius = isRelativeRadius ? frame.height * cornerRadius : cornerRadius
        layer.borderColor = borderColor.cgColor
        layer.borderWidth = borderWidth
    }
}