Restrict size of NSTextAttachment image - swift

Question

I am trying to insert an image in UITextView. I have used the following code.
extension TextView {
func add(image: UIImage) {
let attachment = NSTextAttachment()
attachment.image = image
attachment.bounds = CGRect(x: 0, y: 0, width: 40, height: 40)
let attString = NSAttributedString(attachment: attachment)
self.attributedText = attString
}
}
The parent UIViewController calls add(image: UIImage).
In func textViewDidChange(_ textView: UITextView), I save the attributedText in CoreData as a Transforable NSAttributedString. I use
NSAttributedStringTransformer for Transformer
The image's size is 40X40 when added. The image has also the same size when I dismiss the parent UIViewController and present it back. However, if I quit the app and relaunch it, the image is not 40X40. It is larger than then UIScreen's size.
How to set size of the image to be 40X40 even after quitting the app?

Answer 1

By setting attachment bounds, you are not resizing the actual image, just the display bounds. Looks like the attributed string transformer doesn’t serialize the bounds you set. You will have to either resize the image directly, or extend the transformer to add the bounds after deserializing from data.
Edit: I see that NSAttributedStringTransformer is not an Apple-provided transformer. So take a look at the source code and see why the bounds are not serialized properly.