Swift UIView Subviews not rounding corners in Custom UIView Subclass - ios

Question

Greetings stack overflow.
I am trying to build a "bullseye" type view, using coloured subviews and the corner radius. The problem I have is, only my first subview's corners are getting rounded and the inner views are still squares. The black view is a subview of my custom view. The red view is it's subview, and they yellow view the subview of that. Pretty simple hierarchy.
The result looks like this:
I add the views and set their constraints manually. My test app just has the ThreeCircleView dead center of a view controller with the X,Y centered and the width, height constant. I do the actual rounding of the corners in didLayoutSubViews because the size of the view might change, so the corners would have to be resized.
I wrote a test view to isolate this, here it is
class ThreeCircleView: UIView {
var outerCircle: UIView = UIView()
var middleCircle: UIView = UIView()
var innerCircle: UIView = UIView()
override init(frame: CGRect) {
super.init(frame: frame)
translatesAutoresizingMaskIntoConstraints = false
addSubViews()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
translatesAutoresizingMaskIntoConstraints = false
addSubViews()
}
func addSubViews() {
outerCircle.backgroundColor = .black
middleCircle.backgroundColor = .red
innerCircle.backgroundColor = .yellow
self.addSubview(outerCircle)
outerCircle.addSubview(middleCircle)
middleCircle.addSubview(innerCircle)
let outerCenterY = outerCircle.centerYAnchor.constraint(equalTo: self.centerYAnchor)
let outerCenterX = outerCircle.centerXAnchor.constraint(equalTo: self.centerXAnchor)
let outerCenterWidth = outerCircle.widthAnchor.constraint(equalTo: self.widthAnchor, constant: -50.0 )
let outerCenterHeight = outerCircle.heightAnchor.constraint(equalTo: self.heightAnchor, constant: -50.0 )
outerCircle.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([outerCenterY,outerCenterX,outerCenterWidth,outerCenterHeight])
self.setNeedsLayout()
let middleCenterY = middleCircle.centerYAnchor.constraint(equalTo: self.centerYAnchor)
let middleCenterX = middleCircle.centerXAnchor.constraint(equalTo: self.centerXAnchor)
let middleCenterWidth = middleCircle.widthAnchor.constraint(equalTo: self.widthAnchor, constant: -100.0 )
let middleCenterHeight = middleCircle.heightAnchor.constraint(equalTo: self.heightAnchor, constant: -100.0 )
middleCircle.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([middleCenterY,middleCenterX,middleCenterWidth,middleCenterHeight])
let innerCenterY = innerCircle.centerYAnchor.constraint(equalTo: self.centerYAnchor)
let innerCenterX = innerCircle.centerXAnchor.constraint(equalTo: self.centerXAnchor)
let innerCenterWidth = innerCircle.widthAnchor.constraint(equalTo: self.widthAnchor, constant: -150.0 )
let innerCenterHeight = innerCircle.heightAnchor.constraint(equalTo: self.heightAnchor, constant: -150.0 )
innerCircle.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([innerCenterY,innerCenterX,innerCenterWidth,innerCenterHeight])
}
func makeCircle(v:UIView) {
v.layer.cornerRadius = v.frame.size.width * 0.50
v.clipsToBounds = true
}
override func layoutSubviews() {
super.layoutSubviews()
makeCircle(v: outerCircle)
makeCircle(v: middleCircle)
makeCircle(v: innerCircle)
}
}

Answer 1

An easy way to make it look as expected is to add layoutIfNeeded() call inside your makeCircle(v:UIView) method. This will make you sure that all views' frames are updated correctly before applying visual changes:
func makeCircle(v:UIView) {
v.layoutIfNeeded()
v.layer.cornerRadius = v.frame.size.width * 0.50
v.clipsToBounds = true
}