在UIView中绘制圆形切口（快速）

Question

I'm trying to make a UIView that is a black color with a transparent circle in the middle. My code so far:

class MyView: UIView {

    override var frame: CGRect {
        didSet {
            setNeedsDisplay()
        }
    }

  override func pointInside(point: CGPoint, withEvent event: UIEvent?) -> Bool {
        for subview in subviews as [UIView] {
            if !subview.hidden && subview.alpha > 0 && subview.userInteractionEnabled && subview.pointInside(convertPoint(point, toView: subview), withEvent: event) {
                return true
            }
        }
        return false
    }



    override func drawRect(rect: CGRect) {

        let contextRef = UIGraphicsGetCurrentContext()
        let circleRect = CGRect(x: 67, y: 214, width: 240, height: 240)
        CGContextAddEllipseInRect(contextRef, circleRect)
        CGContextClip(contextRef)

        CGContextSetRGBFillColor(contextRef, 0.0, 0.0, 0.0, 0.6)
        CGContextFillRect(contextRef, rect)



    }

}

In my UIViewController I init the view like so:

let blackView = MyView()
blackView.frame = view.frame
view.addSubview(blackView)

I just have an entirely black screen with no cutout. What am I doing wrong here? An pointers would be greatly appreciated! thanks.

EDIT: I need to be doing this in drawRect if possible and not adding a layer as I am forwarding touch events using pointsInside.

Answer 1

Instead of overriding drawRect , use CAShapeLayer as mask:

let blackView = UIView()
blackView.frame = view.frame
let mask = CAShapeLayer()
mask.path = UIBezierPath(ovalInRect: CGRectInset(view.frame, 30, 30)).CGPath
blackView.layer.mask = mask