blurred screen with circle mask

circleBlurMask.swift

    @IBOutlet var mapView: MKMapView!
    func setupMapBlur () {
        var blur: UIView!
        
        if ios8() {
            blur = UIVisualEffectView (effect: UIBlurEffect (style: UIBlurEffectStyle.Light))
        } else {
            blur = FXBlurView (frame: view.frame)
        }
        
        blur.frame = view.frame
        blur.userInteractionEnabled = false
        view.addSubview(blur)
        
        let circleSize: CGFloat = 300

        let path = UIBezierPath (
            roundedRect: blur.frame,
            cornerRadius: 0)
        
        let circle = UIBezierPath (
            roundedRect: CGRect (origin: CGPoint (x: blur.center.x - circleSize/2, y: 30),
                size: CGSize (width: circleSize, height: circleSize)), cornerRadius: circleSize/2)
        
        path.appendPath(circle)
        path.usesEvenOddFillRule = true
        
        let maskLayer = CAShapeLayer ()
        maskLayer.path = path.CGPath
        maskLayer.fillRule = kCAFillRuleEvenOdd
        
        let borderLayer = CAShapeLayer ()
        borderLayer.path = circle.CGPath
        borderLayer.strokeColor = UIColor.whiteColor().CGColor
        borderLayer.lineWidth = 5
        blur.layer.addSublayer(borderLayer)
        
        blur.layer.mask = maskLayer
    }
    
    func ios8 () -> Bool {
        let version = UIDevice().systemVersion
        let major = version.componentsSeparatedByString(".")[0]
        
        if major == "8" {
            return true
        } else {
            return false
        }
    }