layoutIfNeeded called on iOS10 but not iOS9

Question

I am using layoutIfNeeded to do some view setup within a UITableViewCell . eg:

override func layoutIfNeeded() {
  super.layoutIfNeeded()
  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
}

This works fine in iOS10 however I've noticed layoutIfNeeded is not called at all in iOS9! Why is this? What can I do to get around it, or where should I place this setup code instead?

Answer 1

Your layout code should be in layoutSubviews , which will be called automatically. You can also call setNeedsLayout and/or layoutIfNeeded to trigger layout, but you should not rely on either of those being called by anyone else.