How do I create a UIView with a transparent circle inside (in swift)?

Question

I want to create a view that looks like this:

I figure what I need is a uiview with some sort of

Answer 1

The above solution works great.

Say if you are looking for mask with rectangle area here is the snippet below

let fWidth = self.frame.size.width
let fHeight = self.frame.size.height
let squareWidth = fWidth/2
let topLeft = CGPoint(x: fWidth/2-squareWidth/2, y: fHeight/2-squareWidth/2)
let topRight = CGPoint(x: fWidth/2+squareWidth/2, y: fHeight/2-squareWidth/2)
let bottomLeft = CGPoint(x: fWidth/2-squareWidth/2, y: fHeight/2+squareWidth/2)
let bottomRight = CGPoint(x: fWidth/2+squareWidth/2, y: fHeight/2+squareWidth/2)
let cornerWidth = squareWidth/4


// Step 2
let path = CGMutablePath()
path.addRoundedRect(in: CGRect(x: topLeft.x, y: topLeft.y,
  width: topRight.x - topLeft.x, height: bottomLeft.y - topLeft.y),
 cornerWidth: 20, cornerHeight: 20)


path.addRect(CGRect(origin: .zero, size: self.frame.size))
// Step 3
let maskLayer = CAShapeLayer()
maskLayer.backgroundColor = UIColor.clear.cgColor
maskLayer.path = path
// For Swift 4.0
maskLayer.fillRule = kCAFillRuleEvenOdd
// For Swift 4.2
//maskLayer.fillRule = .evenOdd
// Step 4
self.layer.mask = maskLayer
self.clipsToBounds = true

rectangle mask looks like this