Text Attachments

    override func viewDidLoad() {
        super.viewDidLoad()

        title = "Attachment"

        let attachmentCharacter = String(Character(UnicodeScalar(NSAttachmentCharacter)))
        let text = NSMutableAttributedString(string: "This is our image:\n\n\(attachmentCharacter)\n\nAfter the image.", attributes: [
            NSFontAttributeName: UIFont.systemFontOfSize(18)
        ])

        let attachment = NSTextAttachment()
        attachment.image = UIImage(named: "Photo")
        text.addAttribute(NSAttachmentAttributeName, value: attachment, range: NSRange(location: 20, length: 1))

        textView.attributedText = text
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        let textRange = NSRange(location: 0, length: textView.attributedText.length)
        textView.attributedText.enumerateAttribute(NSAttachmentAttributeName, inRange: textRange, options: []) { [weak self] value, range, _ in
            guard let attachment = value as? NSTextAttachment else { return }

            if let bounds = self?.boundsForAttachment(attachment), layoutManger = self?.textView.layoutManager {
                attachment.bounds = bounds

                let invalidRange = NSRange(location: range.location, length: textRange.length - range.location)
                layoutManger.invalidateLayoutForCharacterRange(invalidRange, actualCharacterRange: nil)
            }
        }
    }


    // MARK: - Private

    private func boundsForAttachment(attachment: NSTextAttachment) -> CGRect? {
        guard let image = attachment.image else { return nil }

        // Assuming landscape
        let width = textView.textContainer.size.width - (textView.textContainer.lineFragmentPadding * 2)
        return CGRect(x: 0, y: 0, width: width, height: image.size.height / image.size.width * width)
    }