Inverted View

InvertedView.swift

//: Playground - noun: a place where people can play

import UIKit
import XCPlayground

func mask(viewToMask: UIView, maskRect: CGRect, invert: Bool = false) {
    let maskLayer = CAShapeLayer()
    let path = CGPathCreateMutable()
    if (invert) {
        CGPathAddRect(path, nil, viewToMask.bounds)
    }
    CGPathAddRoundedRect(path, nil, maskRect, 4.0, 4.0)
    //        CGPathAddRect(path, nil, maskRect)
    
    maskLayer.path = path
    if (invert) {
        maskLayer.fillRule = kCAFillRuleEvenOdd
    }
    
    // Set the mask of the view.
    viewToMask.layer.mask = maskLayer;
}

class MyViewController: UIViewController {
    
    var overlay: UIView = {
        let view = UIView(frame: CGRect(x: 0, y: 0, width: 400, height: 700))
        view.backgroundColor = UIColor.blackColor()
        view.alpha = 0.4
        return view
    }()
    
    var window: UIView = {
        let view = UIView(frame: CGRect(x: 50, y: 100, width: 275, height: 200))
        view.backgroundColor = UIColor.clearColor()
        return view
    }()
    
    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor.whiteColor()
        view.addSubview(overlay)
        view.addSubview(window)
        mask(overlay, maskRect: window.frame, invert: true)
    }
    
}


XCPlaygroundPage.currentPage.liveView = MyViewController()