title: Corners not rounding for button in UITableViewCell
body: <p>I'm trying to round a button's bottom corners by calling this method in <code>layoutSubviews</code> for a <code>UITableViewCell</code>:</p>
  
  <pre><code>func styleRescueButton() {
      let rescueButtonCornerLayer = CAShapeLayer()
      let rescueButtonRoundedCornersPath = UIBezierPath(roundedRect: rescueNowButton.bounds, byRoundingCorners: [UIRectCorner.bottomLeft, UIRectCorner.bottomRight], cornerRadii: CGSize(width: MyTheme.cornerRadius, height: MyTheme.cornerRadius))
      rescueButtonCornerLayer.path = rescueButtonRoundedCornersPath.cgPath
      rescueNowButton.layer.mask = rescueButtonCornerLayer
      rescueNowButton.clipsToBounds = true
      rescueNowButton.layer.masksToBounds = true
  }
  </code></pre>
  
  <p>it's not working at all though, the corners are not rounding. What am I doing wrong here?</p>