Swift - After adding a custom Curve extension, it does not render programmatically created views, only views created with Interface Builder - swift

Question

I have an extension to curve the bottom edge of views since this styling is used on multiple screens in the app I am trying to create.
However, I have noticed I can only make it work with views that I have added trough interface builder. If I try to apply it on view created programmatically they do not render.
I have created a simple example to illustrate the problem. The main storyboard contains two viewControllers with a single colored view in the middle: one created with Interface Builder while the other programmatically.
In StoryboardVC, the view with the curve is rendered correctly without any problem. The setBottomCurve() method is used to create the curve.
If you compare this to setting the entry point to ProgrammaticVC, running the app you can see a plain white screen. Comment this line out to see the view appear again.
This is the extension used:
extension UIView {
func setBottomCurve(curve: CGFloat = 40.0){
self.frame = self.bounds
let rect = self.bounds
let y:CGFloat = rect.size.height - curve
let curveTo:CGFloat = rect.size.height
let myBezier = UIBezierPath()
myBezier.move(to: CGPoint(x: 0, y: y))
myBezier.addQuadCurve(to: CGPoint(x: rect.width, y: y), controlPoint: CGPoint(x: rect.width / 2, y: curveTo))
myBezier.addLine(to: CGPoint(x: rect.width, y: 0))
myBezier.addLine(to: CGPoint(x: 0, y: 0))
myBezier.close()
let maskForPath = CAShapeLayer()
maskForPath.path = myBezier.cgPath
layer.mask = maskForPath
}
}
I expect ProgrammaticVC to look identical to StoryboardVC (except for the difference in color)
The example project can be found here:
https://github.com/belamatedotdotipa/CurveTest2

Answer 1

I suggest to create a subclass instead of using an extension, this is a specific behaviour.
In this case you cannot see the result expected, when you are adding the view programmatically, because in the viewDidLoad you don't have the frame of your view, in this example you can use the draw function:
class BottomCurveView: UIView {
#IBInspectable var curve: CGFloat = 40.0 {
didSet {
setNeedsLayout()
}
}
override func draw(_ rect: CGRect) {
setBottomCurve()
}
private func setBottomCurve() {
let rect = bounds
let y: CGFloat = rect.size.height - curve
let curveTo: CGFloat = rect.size.height
let myBezier = UIBezierPath()
myBezier.move(to: CGPoint(x: 0, y: y))
myBezier.addQuadCurve(to: CGPoint(x: rect.width, y: y), controlPoint: CGPoint(x: rect.width / 2, y: curveTo))
myBezier.addLine(to: CGPoint(x: rect.width, y: 0))
myBezier.addLine(to: CGPoint(x: 0, y: 0))
myBezier.close()
let maskForPath = CAShapeLayer()
maskForPath.path = myBezier.cgPath
layer.mask = maskForPath
}
}