Drop-in UIAlertController replacement with embedded UITextView

TextViewAlertController.swift

//
//  TextViewAlertController.swift
//  TextViewAlertController
//
//  Created by Davide Toldo on 01.11.19.
//  Copyright © 2019 Davide Toldo. All rights reserved.
//
import UIKit

class TextViewAlertController: UIAlertController {

    let textView: UITextView = {
        let view = UITextView(frame: CGRect.zero)
        view.layer.cornerRadius = 5
        view.layer.masksToBounds = true
        view.translatesAutoresizingMaskIntoConstraints = false
        return view
    }()
    
    var keyboardHeight: CGFloat = 100 {
        didSet {
            let height = UIScreen.main.bounds.height
            let menu = self.view.frame.height
            let keyb = self.keyboardHeight
            self.view.frame.origin.y = height-menu-keyb-20
        }
    }
    
    convenience init(title: String?) {
        self.init(title: title, message: "\n\n\n\n\n\n", preferredStyle: .alert)
    }
    
    override var preferredStyle: UIAlertController.Style {
        return .alert
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        view.addSubview(textView)
        
        [textView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 8),
        textView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -8),
        textView.topAnchor.constraint(equalTo: view.topAnchor, constant: 64),
        textView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -64)].forEach({ $0.isActive = true })
        
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardChange(sender:)), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardChange(sender:)), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardChange(sender:)), name: UIResponder.keyboardWillHideNotification, object: nil)
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillChangeFrameNotification, object: nil)
        NotificationCenter.default.removeObserver(self, name: UIResponder.keyboardWillHideNotification, object: nil)
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        textView.becomeFirstResponder()
        UIView.animate(withDuration: 0.3) {
            let height = UIScreen.main.bounds.height
            let menu = self.view.frame.height
            let keyb = self.keyboardHeight
            self.view.frame.origin.y = height-menu-keyb-20
        }
    }
    
    @objc func keyboardChange(sender: Notification) {
        guard let userInfo = sender.userInfo else { return }
        let endFrame = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? CGRect
        keyboardHeight = endFrame?.height ?? 100
    }
}