높이의 Relation을 Greater than 으로 바꿔준다.
func textViewDidChange(_ textView: UITextView) {
let size = CGSize(width: view.frame.width, height: .greatestFiniteMagnitude)
let estimatedSize = textView.sizeThatFits(size)
textView.constraints.forEach { (constraint) in
if constraint.firstAttribute == .height {
constraint.constant = estimatedSize.height
}
}
}