Modern implementation of KeyboardAvoidingViewController

KeyboardAvoidingViewController.swift

import UIKit

open class KeyboardAvoidingViewController: UIViewController {

  private var observers: [NSObjectProtocol] = []

  open override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    let nc = NotificationCenter.default
    var observer = nc.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: .main) { [weak self] note in
      self?.animateSafeAreaInsetsForKeyboard(note.userInfo!)
    }
    observers.append(observer)
    observer = nc.addObserver(forName: UIResponder.keyboardWillHideNotification, object: nil, queue: .main) { [weak self] note in
      self?.animateSafeAreaInsetsForKeyboard(note.userInfo!)
    }
    observers.append(observer)
  }

  open override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)
    observers.forEach(NotificationCenter.default.removeObserver)
    observers = []
  }

  // MARK: Keyboard Observing
  
  func animateSafeAreaInsetsForKeyboard(_ userInfo: [AnyHashable: Any]) {
    //swiftlint:disable force_cast force_unwrapping
    let keyboardFrameEnd = userInfo[UIResponder.keyboardFrameEndUserInfoKey]! as! CGRect
    let animationDuration = userInfo[UIResponder.keyboardAnimationDurationUserInfoKey]! as! TimeInterval
    let animationCurve = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey]! as! Int
    let animationOptions = UIView.AnimationOptions(rawValue: UInt(animationCurve << 16))
    self.additionalSafeAreaInsets.bottom = keyboardFrameEnd.height - self.view.safeAreaInsets.bottom
    UIView.animate(withDuration: animationDuration, delay: 0, options: animationOptions, animations: { [weak self] in
      self?.view.layoutIfNeeded()
    }, completion: nil)
    //swiftlint:enable force_cast force_unwrapping
  }
}