problem description

after textView append an attributeString with the code, continue to edit the keyboard, the style cannot be restored

related codes

button is as follows:

let attributeText = NSMutableAttributedString(attributedString: textView.attributedText)
attributeText.append(NSAttributedString(string: "@", attributes: [NSAttributedString.Key.foregroundColor: UIColor.cyan]))
self.textView.attributedText = attributeText

what result do you expect? What is the error message actually seen?

I want textView to revert to its original style when it is re-edited