SWIFT 3 - CGImage to PNG - ios

Question

I am trying to use a color mask to make a color in JPG image transparent because as I read, color mask only works with JPG.
This code work when I apply the color mask and save the image as a JPG, but as a JPG, there is no transparency so I want to transform the JPG image to a PNG image to keep the transparency but when I try to do it, the color mask doesn't work.
Am I doing something wrong or maybe this isn't the right approach.
Here is the code of the 2 functions :
func callChangeColorByTransparent(_ sender: UIButton){
var colorMasking: [CGFloat] = []
if let textLabel = sender.titleLabel?.text {
switch textLabel {
case "Remove Black":
colorMasking = [0,30,0,30,0,30]
break
case "Remove Red":
colorMasking = [180,255,0,50,0,60]
break
default:
colorMasking = [222,255,222,255,222,255]
}
}
print(colorMasking)
let newImage = changeColorByTransparent(selectedImage, colorMasking: colorMasking)
symbolImageView.image = newImage
}
func changeColorByTransparent(_ image : UIImage, colorMasking : [CGFloat]) -> UIImage {
let rawImage: CGImage = (image.cgImage)!
//let colorMasking: [CGFloat] = [222,255,222,255,222,255]
UIGraphicsBeginImageContext(image.size)
let maskedImageRef: CGImage = rawImage.copy(maskingColorComponents: colorMasking)!
if let context = UIGraphicsGetCurrentContext() {
context.draw(maskedImageRef, in: CGRect(x: 0, y: 0, width: image.size.width, height: image.size.height))
var newImage = UIImage(cgImage: maskedImageRef, scale: image.scale, orientation: image.imageOrientation)
UIGraphicsEndImageContext()
var pngImage = UIImage(data: UIImagePNGRepresentation(newImage)!, scale: 1.0)
return pngImage!
}
print("fail")
return image
}
Thank for your help.

Answer 1

Thanks the issue of DonMag in my other question SWIFT 3 - CGImage copy always nil, here is the code to solve this :
func saveImageWithAlpha(theImage: UIImage, destFile: URL) -> Void {
// odd but works... solution to image not saving with proper alpha channel
UIGraphicsBeginImageContext(theImage.size)
theImage.draw(at: CGPoint.zero)
let saveImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
if let img = saveImage, let data = UIImagePNGRepresentation(img) {
try? data.write(to: destFile)
}
}