Swift blur extension on UIImage crashes - swift

Question

I have written an extension for UIImage and get nil for the context. Any idea what could be the problem?
public func blur(size: Float) -> UIImage! {
let boxSize = size - (size % 2) + 1
let image = self.CGImage
let inProvider = CGImageGetDataProvider(image)
let height = vImagePixelCount(CGImageGetHeight(image))
let width = vImagePixelCount(CGImageGetWidth(image))
let rowBytes = CGImageGetBytesPerRow(image)
let inBitmapData = CGDataProviderCopyData(inProvider)
let inData = UnsafeMutablePointer<Void>(CFDataGetBytePtr(inBitmapData))
var inBuffer = vImage_Buffer(data: inData, height: height, width: width, rowBytes: rowBytes)
let outData = malloc(CGImageGetBytesPerRow(image) * CGImageGetHeight(image))
var outBuffer = vImage_Buffer(data: outData, height: height, width: width, rowBytes: rowBytes)
let _ = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, nil, 0, 0, UInt32(boxSize), UInt32(boxSize), nil, vImage_Flags(kvImageEdgeExtend))
let colorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGBitmapContextCreate(outBuffer.data, Int(outBuffer.width), Int(outBuffer.height), 8, outBuffer.rowBytes, colorSpace, CGImageGetBitmapInfo(image).rawValue)
let imageRef = CGBitmapContextCreateImage(context)!
let bluredImage = UIImage(CGImage: imageRef)
free(outData)
return bluredImage
}

Answer 1

The problem was to do the blur on CGImage not UIImage directly:
extension UIImage {
class func blurEffect(cgImage: CGImageRef) -> UIImage! {
return UIImage(CGImage: cgImage)
}
func blurEffect(boxSize: CGFloat) -> UIImage! {
return UIImage(CGImage: bluredCGImage(boxSize))
}
func bluredCGImage(boxSize: CGFloat) -> CGImageRef! {
return CGImage!.blurEffect(boxSize)
}
}
extension CGImage {
func blurEffect(boxSize: CGFloat) -> CGImageRef! {
let boxSize = boxSize - (boxSize % 2) + 1
let inProvider = CGImageGetDataProvider(self)
let height = vImagePixelCount(CGImageGetHeight(self))
let width = vImagePixelCount(CGImageGetWidth(self))
let rowBytes = CGImageGetBytesPerRow(self)
let inBitmapData = CGDataProviderCopyData(inProvider)
let inData = UnsafeMutablePointer<Void>(CFDataGetBytePtr(inBitmapData))
var inBuffer = vImage_Buffer(data: inData, height: height, width: width, rowBytes: rowBytes)
let outData = malloc(CGImageGetBytesPerRow(self) * CGImageGetHeight(self))
var outBuffer = vImage_Buffer(data: outData, height: height, width: width, rowBytes: rowBytes)
vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, nil, 0, 0, UInt32(boxSize), UInt32(boxSize), nil, vImage_Flags(kvImageEdgeExtend))
let colorSpace = CGColorSpaceCreateDeviceRGB()
let context = CGBitmapContextCreate(outBuffer.data, Int(outBuffer.width), Int(outBuffer.height), 8, outBuffer.rowBytes, colorSpace, CGImageGetBitmapInfo(self).rawValue)
let imageRef = CGBitmapContextCreateImage(context)
free(outData)
return imageRef
}
}