Blurring images with UIVisualEffectView

blur.swift

//
//  BlurredImageGenerator.swift
//
//  Copyright (c) 2015 Matt Rajca. All rights reserved.
//

import UIKit

func generateBlurredImageFromImage(image: UIImage) -> UIImage {
	let sourceImageRect = CGRectMake(0, 0, image.size.width, image.size.height)
	
	var window: UIWindow! = UIWindow(frame: sourceImageRect)
	window.windowLevel = -1000 // place the temporary window offscreen
	
	let parent = UIView(frame: sourceImageRect)
	let imageView = UIImageView(frame: sourceImageRect)
	imageView.image = image
	
	let blurView = UIVisualEffectView(effect: UIBlurEffect(style: .Dark))
	blurView.frame = sourceImageRect
	imageView.addSubview(blurView)
	
	parent.addSubview(imageView)
	
	let vc = UIViewController()
	vc.view = parent
	
	window.rootViewController = vc
	window.makeKeyAndVisible()
	
	UIGraphicsBeginImageContextWithOptions(sourceImageRect.size, false, 1 /* don't blow up the image coordinates */)
	window.drawViewHierarchyInRect(sourceImageRect, afterScreenUpdates: true)
	let snapshotImage = UIGraphicsGetImageFromCurrentImageContext()
	UIGraphicsEndImageContext()
	
	window = nil
	
	return snapshotImage
}