UIImagePNGRepresentation issues? / Images rotated by 90 degrees

Question

I want to load images from UIImagePickerController, then save the selected photo to my app\'s document directory.

UIImage *image = [info objectForKey:UIImage         


        

Answer 1

I have created this UIImage extension to fix this problem with UIImagePNGRepresentation, based on this response. So I propose to use this class func UIImage.PNGRepresentation(img: UIImage) instead of UIKit func UIImagePNGRepresentation.

Swift 3 code :

//  MyUIImage.swift
//  MyEasyMovie-Public-App
//
//  Created by Ahmed Zahraz on 19/12/2016.
//  Copyright © 2016 AhmedZahraz. All rights reserved.    

import Foundation
import UIKit

extension UIImage {


    public class func PNGRepresentation(_ img: UIImage) -> Data? {
        // No-op if the orientation is already correct
        if (img.imageOrientation == UIImageOrientation.up) {
            return UIImagePNGRepresentation(img);
        }
        // We need to calculate the proper transformation to make the image upright.
        // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
        var transform:CGAffineTransform = CGAffineTransform.identity

        if (img.imageOrientation == UIImageOrientation.down
            || img.imageOrientation == UIImageOrientation.downMirrored) {

            transform = transform.translatedBy(x: img.size.width, y: img.size.height)
            transform = transform.rotated(by: CGFloat(M_PI))
        }

        if (img.imageOrientation == UIImageOrientation.left
            || img.imageOrientation == UIImageOrientation.leftMirrored) {

            transform = transform.translatedBy(x: img.size.width, y: 0)
            transform = transform.rotated(by: CGFloat(M_PI_2))
        }

        if (img.imageOrientation == UIImageOrientation.right
            || img.imageOrientation == UIImageOrientation.rightMirrored) {

            transform = transform.translatedBy(x: 0, y: img.size.height);
            transform = transform.rotated(by: CGFloat(-M_PI_2));
        }

        if (img.imageOrientation == UIImageOrientation.upMirrored
            || img.imageOrientation == UIImageOrientation.downMirrored) {

            transform = transform.translatedBy(x: img.size.width, y: 0)
            transform = transform.scaledBy(x: -1, y: 1)
        }

        if (img.imageOrientation == UIImageOrientation.leftMirrored
            || img.imageOrientation == UIImageOrientation.rightMirrored) {

            transform = transform.translatedBy(x: img.size.height, y: 0);
            transform = transform.scaledBy(x: -1, y: 1);
        }


        // Now we draw the underlying CGImage into a new context, applying the transform
        // calculated above.
        let ctx:CGContext = CGContext(data: nil, width: Int(img.size.width), height: Int(img.size.height),
                                      bitsPerComponent: img.cgImage!.bitsPerComponent, bytesPerRow: 0,
                                      space: img.cgImage!.colorSpace!,
                                      bitmapInfo: img.cgImage!.bitmapInfo.rawValue)!

        ctx.concatenate(transform)


        if (img.imageOrientation == UIImageOrientation.left
            || img.imageOrientation == UIImageOrientation.leftMirrored
            || img.imageOrientation == UIImageOrientation.right
            || img.imageOrientation == UIImageOrientation.rightMirrored
            ) {


            ctx.draw(img.cgImage!, in: CGRect(x:0,y:0,width:img.size.height,height:img.size.width))

        } else {
            ctx.draw(img.cgImage!, in: CGRect(x:0,y:0,width:img.size.width,height:img.size.height))
        }


        // And now we just create a new UIImage from the drawing context
        let cgimg:CGImage = ctx.makeImage()!
        let imgEnd:UIImage = UIImage(cgImage: cgimg)

        return UIImagePNGRepresentation(imgEnd)
    }

}