UIImage resizing via an extension - ios

Question

I have this UIImage resizing extension
extension UIImage {
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / image.size.width
let heightRatio = targetSize.height / image.size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
I tried to resize an image by calling the extension like below
let logoView: UIImageView = {
let LV = UIImageView()
let thumbnail = resizeImage(image: "DN", CGSize.init(width:70, height:70))
LV.image = thumbnail
LV.contentMode = .scaleAspectFill
LV.layer.masksToBounds = true
return LV
}()
However the Xcode is not allowing me to call the resizing function extension. How can I properly resize the image?
func setupViews() {
addSubview(logoView)
}

Answer 1

Functions in extensions are not standalone functions but tied to the thing they extend. In your case, you're adding a function to UIImage but you are calling it like a standalone function.
To fix, your function should be like this:
extension UIImage {
func resizeImage(targetSize: CGSize) -> UIImage {
// the image is now “self” and not “image” as you original wrote
...
}
}
and you would call it like:
let logoView: UIImageView = {
let LV = UIImageView()
let image = UIImage(named: "DN")
if let image = image {
let thumbnail = image.resizeImage(CGSize.init(width:70, height:70))
LV.image = thumbnail
LV.contentMode = .scaleAspectFill
LV.layer.masksToBounds = true
}
return LV
}()