How to subclass NSTextAttachment?

Question

Here is my problem:

I use Core Data to store rich text input from iOS and/or OS X apps and would like images pasted into the NSTextView or UITextView to: a) retain t

Answer 1

Swift 3 (based on @Bluezen's answer):

class MyTextAttachment : NSTextAttachment {

    override func attachmentBounds(for textContainer: NSTextContainer?, proposedLineFragment lineFrag: CGRect, glyphPosition position: CGPoint, characterIndex charIndex: Int) -> CGRect {

        guard let image = self.image else {
            return CGRect.zero
        }

        let height = lineFrag.size.height

        // Scale how you want
        var scalingFactor = CGFloat(0.8)
        let imageSize = image.size
        if height < imageSize.height {
            scalingFactor *= height / imageSize.height
        }
        let rect = CGRect(x: 0, y: 0, width: imageSize.width * scalingFactor, height: imageSize.height * scalingFactor)

        return rect
    }

}

Note that I am scaling based on height, as I was getting a lineFrag width value of 10000000 in my particular use case. Also note that I replaced scalingFactor = ... with scalingFactor *= ... so that I could use an additional, non-unity scaling factor (0.8 in this case).