ComposedCornerView.swift

/// For Transition
public final class ComposedCornerView: CodeBasedView {

  private let topRightMaskView = UIView()
  private let topLeftMaskView = UIView()
  private let bottomRightMaskView = UIView()
  private let bottomLeftMaskView = UIView()

  private let topRightView = UIView()
  private let topLeftView = UIView()
  private let bottomRightView = UIView()
  private let bottomLeftView = UIView()

  public init() {
    super.init(frame: .zero)

    [
      topRightMaskView,
      topLeftMaskView,
      bottomRightMaskView,
      bottomLeftMaskView,
    ].forEach {
      $0.backgroundColor = .black
    }

    [
      topRightView,
      topLeftView,
      bottomRightView,
      bottomLeftView,
    ].forEach {
      addSubview($0)
      $0.backgroundColor = .black
    }

    topRightView.layer.maskedCorners = .layerMaxXMinYCorner
    topLeftView.layer.maskedCorners = .layerMinXMinYCorner
    bottomRightView.layer.maskedCorners = .layerMaxXMaxYCorner
    bottomLeftView.layer.maskedCorners = .layerMinXMaxYCorner

    topRightView.mask = topRightMaskView
    topLeftView.mask = topLeftMaskView
    bottomRightView.mask = bottomRightMaskView
    bottomLeftView.mask = bottomLeftMaskView

  }

  public override func layoutSubviews() {
    super.layoutSubviews()

    [
      topRightView,
      topLeftView,
      bottomRightView,
      bottomLeftView,
    ].forEach {
      $0.frame = bounds
    }

    let width = bounds.width / 2
    let height = bounds.height / 2

    topRightMaskView.frame = .init(x: width, y: 0, width: width, height: height)
    topLeftMaskView.frame = .init(x: 0, y: 0, width: width, height: height)
    bottomRightMaskView.frame = .init(x: width, y: height, width: width, height: height)
    bottomLeftMaskView.frame = .init(x: 0, y: height, width: width, height: height)

    if #available(iOS 13.0, *) {
      if bounds.width == bounds.height {
        setCornerCurve(.circular)
      } else {
        setCornerCurve(.continuous)
      }
    }

}

  @available(iOS 13, *)
  public func setCornerCurve(_ curve: CALayerCornerCurve) {

    [
      topRightView,
      topLeftView,
      bottomRightView,
      bottomLeftView,
    ].forEach {
      $0.layer.cornerCurve = curve
    }

  }

  public func setCorner(radius: CGFloat, mask: CACornerMask) {

    let actualRadius = radius

    if mask.contains(.layerMinXMinYCorner) {
      topLeftView.layer.cornerRadius = actualRadius
    } else {
      topLeftView.layer.cornerRadius = 0
    }

    if mask.contains(.layerMaxXMinYCorner) {
      topRightView.layer.cornerRadius = actualRadius
    } else {
      topRightView.layer.cornerRadius = 0
    }

    if mask.contains(.layerMinXMaxYCorner) {
      bottomLeftView.layer.cornerRadius = actualRadius
    } else {
      bottomLeftView.layer.cornerRadius = 0
    }

    if mask.contains(.layerMaxXMaxYCorner) {
      bottomRightView.layer.cornerRadius = actualRadius
    } else {
      bottomRightView.layer.cornerRadius = 0
    }
  }

}