Swift 3: crop image - ios

Question

I want to crop images from the center with a specific width and height. I found this code in a SO issue but this method resize the image then it crop it. I want to only get my image cropped and not resized. I tried modifying this code but I can't get the result that I want.
//cropImage
func cropToBounds(image: UIImage, width: Double, height: Double) -> UIImage {
let contextImage: UIImage = UIImage(cgImage: image.cgImage!)
let contextSize: CGSize = contextImage.size
var posX: CGFloat = 0.0
var posY: CGFloat = 0.0
var cgwidth: CGFloat = CGFloat(width)
var cgheight: CGFloat = CGFloat(height)
// See what size is longer and create the center off of that
if contextSize.width > contextSize.height {
posX = ((contextSize.width - contextSize.height) / 2)
posY = 0
cgwidth = contextSize.height
cgheight = contextSize.height
} else {
posX = 0
posY = ((contextSize.height - contextSize.width) / 2)
cgwidth = contextSize.width
cgheight = contextSize.width
}
let rect: CGRect = CGRect(x: posX, y: posY, width: cgwidth, height: cgheight)
// Create bitmap image from context using the rect
let imageRef: CGImage = contextImage.cgImage!.cropping(to: rect)!
// Create a new image based on the imageRef and rotate back to the original orientation
let image: UIImage = UIImage(cgImage: imageRef, scale: image.scale, orientation: image.imageOrientation)
return image
}
How can I do that?

Answer 1

It should be:
func cropImage(toRect rect:CGRect) -> UIImage? {
var rect = rect
rect.origin.y = rect.origin.y * self.scale
rect.origin.x = rect.origin.x * self.scale
rect.size.width = rect.width * self.scale
rect.size.height = rect.height * self.scale
guard let imageRef = self.cgImage?.cropping(to: rect) else {
return nil
}
let croppedImage = UIImage(cgImage:imageRef)
return croppedImage
}

Answer 2

Make sure image will be cropped in the center.
Include largest crop zone possible given by the width and height.
extension UIImage {
func crop(width: CGFloat = 60, height: CGFloat = 60) -> UIImage {
let scale = min(self.size.width / width, self.size.height / height)
let x = self.size.width > self.size.height
? (self.size.width - width * scale) / 2
: 0
let y = self.size.width > self.size.height
? 0
: (self.size.height - height * scale) / 2
let cropZone = CGRect(x: x, y: y, width: width * scale, height: height * scale)
guard let image: CGImage = self.cgImage?.cropping(to: cropZone) else { return UIImage() }
return UIImage(cgImage: image)
}

Answer 3

I am using this to display image which ratio is different from my frame, so I center it and crop the sides.
extension UIImage {
func cropTo(size: CGSize) -> UIImage {
guard let cgimage = self.cgImage else { return self }
let contextImage: UIImage = UIImage(cgImage: cgimage)
var cropWidth: CGFloat = size.width
var cropHeight: CGFloat = size.height
if (self.size.height < size.height || self.size.width < size.width){
return self
}
let heightPercentage = self.size.height/size.height
let widthPercentage = self.size.width/size.width
if (heightPercentage < widthPercentage) {
cropHeight = size.height*heightPercentage
cropWidth = size.width*heightPercentage
} else {
cropHeight = size.height*widthPercentage
cropWidth = size.width*widthPercentage
}
let posX: CGFloat = (self.size.width - cropWidth)/2
let posY: CGFloat = (self.size.height - cropHeight)/2
let rect: CGRect = CGRect(x: posX, y: posY, width: cropWidth, height: cropHeight)
// Create bitmap image from context using the rect
let imageRef: CGImage = contextImage.cgImage!.cropping(to: rect)!
// Create a new image based on the imageRef and rotate back to the original orientation
let cropped: UIImage = UIImage(cgImage: imageRef, scale: self.scale, orientation: self.imageOrientation)
return cropped
}
}