UITextViewDelegate.swift

extension ViewController: UITextViewDelegate {
    
    private func setupTextView() {
        self.commentTextView.delegate = self
    }
    
    func textViewDidEndEditing(_ textView: UITextView) {
        self.placeHolderLabel.isHidden = !textView.text.isEmpty
    }
    
    func textViewDidChange(_ textView: UITextView) {
        
        var height = self.minHeight
        
        if textView.contentSize.height <= self.minHeight {
            height = self.minHeight
        } else if textView.contentSize.height >= self.maxHeight {
            height = self.maxHeight
        } else {
            height = textView.contentSize.height
        }
        
        self.placeHolderLabel.isHidden = !textView.text.isEmpty
        
        self.commentConstraint.constant = height
        UIView.animate(withDuration: 0.1) {
            self.view.layoutIfNeeded()
        }
    }
    
}