How to clip a UIView with a bezier path? - ios

Question

I'm not totally sure to understand how UIBezierPath is supposed to work.
I have added a simple UIView in the middle of the screen, and I wanted to clip it by adding a mask to its layer. I tried this, thinking I'd get something like a losange in the middle of the view:
override func viewDidLoad() {
super.viewDidLoad()
viewToClip.backgroundColor = .white
let bezierPath = UIBezierPath()
bezierPath.move(to: viewToClip.center)
bezierPath.addLine(to: CGPoint(x: viewToClip.center.x - 5, y: viewToClip.center.y))
bezierPath.addLine(to: CGPoint(x: viewToClip.center.x, y: viewToClip.center.y - 5))
bezierPath.addLine(to: CGPoint(x: viewToClip.center.x + 5, y: viewToClip.center.y))
bezierPath.addLine(to: CGPoint(x: viewToClip.center.x, y: viewToClip.center.y + 5))
bezierPath.close()
let testLayer = CAShapeLayer()
testLayer.path = bezierPath.cgPath
viewToClip.layer.mask = testLayer
}
But instead of that, the view simply disappears from the screen. What am I doing wrong?
Thanks for your help.

Answer 1

Can you try
import UIKit
class bb: UIView {
var once:Bool = true
override func draw(_ rect: CGRect) {
if(once)
{
once = false
self.backgroundColor = .white
let bezierPath = UIBezierPath()
let cen = CGPoint.init(x: self.bounds.size.width/2, y: self.bounds.size.height/2)
bezierPath.move(to: cen)
bezierPath.addLine(to: CGPoint(x: cen.x - 5, y: cen.y))
bezierPath.addLine(to: CGPoint(x: cen.x, y: cen.y - 5))
bezierPath.addLine(to: CGPoint(x: cen.x + 5, y: cen.y))
bezierPath.addLine(to: CGPoint(x: cen.x, y: cen.y + 5))
bezierPath.close()
let testLayer = CAShapeLayer()
testLayer.path = bezierPath.cgPath
testLayer.lineWidth = 1.0
testLayer.strokeColor = UIColor.blue.cgColor
testLayer.fillColor = UIColor.green.cgColor
self.layer.addSublayer(testLayer)
}
}