CircleShapeView.swift

open class CircleShapeView: UIView {
  override open var backgroundColor: UIColor? {
    get {
      guard
        let layer = layer as? CAShapeLayer,
        let cgColor = layer.fillColor
        else { return super.backgroundColor }
      return UIColor(cgColor: cgColor)
    }
    set {
      super.backgroundColor = UIColor.clear
      let newColor = newValue ?? UIColor.clear
      if let layer = layer as? CAShapeLayer {
        layer.fillColor = newColor.cgColor
        layer.strokeColor = newColor.cgColor
      }
    }
  }

  override open class var layerClass: AnyClass {
    get {
      return CAShapeLayer.self
    }
  }

  public required init?(coder: NSCoder) {
    super.init(coder: coder)
    initShape()
  }

  public override init(frame: CGRect) {
    super.init(frame: frame)
    initShape()
  }

  func initShape() {
    guard let layer = layer as? CAShapeLayer else { return }

    let path = UIBezierPath(roundedRect: bounds, cornerRadius: bounds.width / 2).cgPath
    layer.path = path
    layer.fillRule = .nonZero
  }

  override open func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
    guard
      let layer = layer as? CAShapeLayer,
      let path = layer.path
      else { return nil }
    if path.contains(point, using: (layer.fillRule == .evenOdd ? .evenOdd : .winding)) {
      return super.hitTest(point, with:event)
    } else {
      return nil
    }
  }
}