Mask a UIView with a cut-out circle

Question

I’ve created a UIView with a semi-transparent black background to sit across my main app’s view. What I’m aiming for here is to create a cut-out circle shape so

Answer 1

Here is my conversion of the accepted answer in Swift:

public class OverlayView: UIView {
let fillColor: UIColor = UIColor.grayColor()
public var framesToCutOut: Array = [NSValue]()

override public func drawRect(rect: CGRect) {
    super.drawRect(rect)

    fillColor.setFill()
    UIRectFill(rect)

    if let context: CGContextRef = UIGraphicsGetCurrentContext() {
        CGContextSetBlendMode(context, .DestinationOut)

        for value in framesToCutOut {
            let pathRect: CGRect = value.CGRectValue()
            let path: UIBezierPath = UIBezierPath(ovalInRect: pathRect)
            path.fill()
        }

        CGContextSetBlendMode(context, .Normal)
    }
}