@IBDesignable code example

Example: @IBDesignable

@IBDesignable class EllipseView: UIView {
    @IBInspectable var strokeWidth: CGFloat = 0
    @IBInspectable var fillColor: UIColor = UIColor.black
    @IBInspectable var strokeColor: UIColor = UIColor.clear

    override func draw(_ rect: CGRect) {
        guard let context = UIGraphicsGetCurrentContext() else { return }
        let rectangle = bounds.insetBy(dx: strokeWidth / 2, dy: strokeWidth / 2)

        context.setFillColor(fillColor.cgColor)
        context.setStrokeColor(strokeColor.cgColor)
        context.setLineWidth(strokeWidth)

        context.addEllipse(in: rectangle)
        context.drawPath(using: .fillStroke)
    }
}