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swiftimagerotationpngimage-rotation

Rotate downloaded (image.png) before/after saving?

I’m trying to rotate a downloaded image that comes in PNG format with a 4:3 ratio that’s landscape.

I need the image rotated by 90 degrees so it’s portrait with the same dimensions.

I tried the .transform function which worked to start with but doesn’t anymore after adding a scrollView with a lot of settings to allow it to zoom and pan, Id rather not go down the route of editing the srollView content as it took a long time to get all the constrains to work properly to allow free zoom and pan.

After downloading my image I save it to app file. Then it’s loaded for display in another function.

Is it possible to rotate the downloaded file whilst saving so it can be retrieved in the correct way?

I found this in another post which I believe would work with the downloaded image, how can I change the orientation for my need?

func normalizedImage() -> UIImage 

{

  if (self.imageOrientation == UIImageOrientation.Up) { 
      return self;
  }

  UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale);
  let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height)
  self.drawInRect(rect)

  let normalizedImage : UIImage = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext();
  return normalizedImage;
}
Solution

  • If you display the UIImage in an image view you can try modifying the orientation. It is basically the same UIImage but with a flag that is interpreted by UIImageView to rotate the image display.

    let rotated = UIImage(cgImage: image.cgImage!, scale: 1, orientation: .right)

    If you really want to save a new image to disk, you will need to actually redraw the image. Some info is already available here : How to Rotate a UIImage 90 degrees?