Cropping image with Swift and put it on center position

Question

In Swift programming , how do you crop an image and put it on the center afterwards?

This is what I\'ve got so far ... I\'ve successfully crop the image but I want t

Answer 1

The accepted answer only does squares for me. I needed a bit more flexible cropping mechanism so I wrote an extension as follows:

import UIKit

extension UIImage {

func crop(to:CGSize) -> UIImage {

    guard let cgimage = self.cgImage else { return self }

    let contextImage: UIImage = UIImage(cgImage: cgimage)

    guard let newCgImage = contextImage.cgImage else { return self }

    let contextSize: CGSize = contextImage.size

    //Set to square
    var posX: CGFloat = 0.0
    var posY: CGFloat = 0.0
    let cropAspect: CGFloat = to.width / to.height

    var cropWidth: CGFloat = to.width
    var cropHeight: CGFloat = to.height

    if to.width > to.height { //Landscape
        cropWidth = contextSize.width
        cropHeight = contextSize.width / cropAspect
        posY = (contextSize.height - cropHeight) / 2
    } else if to.width < to.height { //Portrait
        cropHeight = contextSize.height
        cropWidth = contextSize.height * cropAspect
        posX = (contextSize.width - cropWidth) / 2
    } else { //Square
        if contextSize.width >= contextSize.height { //Square on landscape (or square)
            cropHeight = contextSize.height
            cropWidth = contextSize.height * cropAspect
            posX = (contextSize.width - cropWidth) / 2
        }else{ //Square on portrait
            cropWidth = contextSize.width
            cropHeight = contextSize.width / cropAspect
            posY = (contextSize.height - cropHeight) / 2
        }
    }

    let rect: CGRect = CGRect(x: posX, y: posY, width: cropWidth, height: cropHeight)

    // Create bitmap image from context using the rect
    guard let imageRef: CGImage = newCgImage.cropping(to: rect) else { return self}

    // 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)

    UIGraphicsBeginImageContextWithOptions(to, false, self.scale)
    cropped.draw(in: CGRect(x: 0, y: 0, width: to.width, height: to.height))
    let resized = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    return resized ?? self
  }
}

You can use it so:

let size = CGSize(width: 300, height: 200)
let image = UIImage(named: "my_great_photo")?.crop(size)

If anyone has ideas how to make the landscape, portrait and square handling a bit better let me know.