Making a capture style button with a UIView and 2 CALayers

gistfile1.swift

class MainController: UIViewController {
  
  @IBOutlet weak var captureButton: UIView?
  
  let BORDER_WIDTH:CGFloat = 4
  let RADIUS_MULTIPLIER:CGFloat = 0.5
  let BUTTON_COLOR = UIColor.redColor().CGColor
  let BUTTON_PRESSED_COLOR = UIColor.whiteColor().CGColor
  let INNER_BUTTON_OFFSET = 0.4

  var outerBtnLayer:CALayer = CALayer()
  var innerBtn:CALayer = CALayer()
  
  override func viewDidLoad() {
    
    let buttonWidth = captureButton!.bounds.size.width;
    let centerPoint:CGPoint = CGPointMake(buttonWidth / 2, buttonWidth / 2)
    
    outerBtnLayer.bounds = captureButton!.frame
    outerBtnLayer.borderColor = BUTTON_COLOR
    outerBtnLayer.borderWidth = BORDER_WIDTH
    outerBtnLayer.cornerRadius = buttonWidth * RADIUS_MULTIPLIER
    outerBtnLayer.masksToBounds = true
    outerBtnLayer.position = centerPoint;
    captureButton?.layer.addSublayer(outerBtnLayer)
    
    innerBtn.bounds = CGRect(x: buttonWidth * 0.2, y: buttonWidth * 0.2, width: buttonWidth * 0.8, height: buttonWidth * 0.8)
    innerBtn.backgroundColor = BUTTON_COLOR
    innerBtn.cornerRadius = innerBtn.bounds.size.width * RADIUS_MULTIPLIER
    innerBtn.masksToBounds = true
    innerBtn.position = centerPoint;
    captureButton?.layer.addSublayer(innerBtn)
    
  }

}