CoreImage extensions

UIViewSnapshot.swift

/*
  Extension for UIView for taking a snapshot and blurring it using CoreImage filters.
*/
extension UIView {
    
    func blurredSnapshot() -> UIImage {
        
        func toCIImage(image: UIImage) -> CIImage {
            return image.CIImage ?? CIImage(CGImage: image.CGImage!)
        }
        
        func toUIImage(image: CIImage) -> UIImage {
            return UIImage(CIImage: image)
        }
        
        UIGraphicsBeginImageContextWithOptions(bounds.size, false, UIScreen.mainScreen().scale)
        drawViewHierarchyInRect(self.bounds, afterScreenUpdates: true)
        
        let image = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        var finalImage:UIImage?
        
        if let ciImage:CIImage = toCIImage(image) {
            
            if let blurredImage:CIImage = ciImage.imageByApplyingFilter("CIGaussianBlur", withInputParameters: [kCIInputRadiusKey : 20]){
                
                // crop blurred image so it is the same as the source snapshot. Otherwise it is larger because of the blurring
                
                if let croppedBlurredImage:CIImage = blurredImage.imageByCroppingToRect(ciImage.extent){
                    
                    finalImage = toUIImage(croppedBlurredImage)
                }
            }
        }
        
        return finalImage ?? image
    }
}