How to get UIImageView's subview (a UIView) to cover it entirely? - ios

Question

I have a UIImageView placed on the storyboard, and am trying to programmatically add a UIView as a subview to it, and have that UIView match the parent UIImageView's size and position exactly so that it covers it.
The UIView is a custom class of UIView thats drawing a CAShapeLayer that fills its frame, if that matters at all.
In addition to the following code, I've also tried "redOverlay.center = parentImage.center" without success.
In my viewdidload() i have:
let redOverlay = RedOverlay(frame: CGRect(x: 0.0, y: 0.0, width: parentImage.bounds.width, height: parentImage.bounds.height))
parentImage.addSubview(redOverlay)
And here is my RedOverlay subclass of UIView if that makes a difference:
import UIKit
extension CGFloat {
func toRadians() -> CGFloat {
return self * CGFloat.pi / 180.0
}
}
class RedOverlay: UIView {
var path: UIBezierPath!
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.darkGray.withAlphaComponent(0.5)
pie()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
func pie() {
path = UIBezierPath()
path.move(to: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/2))
path.addArc(withCenter: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/2),
radius: self.bounds.size.width/2,
startAngle: CGFloat(215).toRadians(),
endAngle: CGFloat(90).toRadians(),
clockwise: true)
path.close()
let shapeLayer = CAShapeLayer()
shapeLayer.path = path.cgPath
shapeLayer.fillColor = UIColor.red.cgColor
shapeLayer.opacity = 0.5
self.layer.addSublayer(shapeLayer)
}
}
The result I get actually works perfectly on iPhone 6, but anything larger like 6s or ipads, and the child UIView is actually noticeably smaller than the UIImageView. In the iPad, the UIView sits well to the left, while in the 6s it is only a bit left.
Basically, it seems like the UIView being generated isnt as wide as the image, even though parentImage.bounds.width was used to determine the UIView's width. I do have "Clip to Bounds" and Aspect Fit set in IB so I don't know why the image would be bigger than it's bounds if thats possible at all.
Whats the cleanest way to get this subview to match the parent view in all device sizes?
EDIT: The solution I found was to call my function pie() (that draws the CAShapeLayer), by overriding layoutSubviews and calling pie() there so that my shapeLayer is updated whenever the view changes. I removed .addSublayer(shapeLayer) from pie() and now I call it in viewdidload in case layoutsubviews being called repeatedly might cause many layers to be created.
override func layoutSubviews() {
super.layoutSubviews()
pie()
}