handle keyboard notifications in swift

Example.swift

class ViewController: UIViewController, KeyboardObserverDelegate {
  
  let keyboardObserver = KeyboardObserver()
  
  let scrollView = UIScrollView()
  
  let randomView = UIView()
  
  func viewDidLoad() {
    super.viewDidLoad()
    
    view.addSubview(scrollView)
    
    keyboardObserver.delegate = self
  }
  
  func keyboardDidChange(_ keyboard: KeyboardNotification) {
    
    if keyboard.willShow {
      scrollView.contentInset.bottom = keyboard.endHeight
      keyboard.animate {
        self.randomView.transform = CGAffineTransform(translateX: 0, translateY: -keyboard.endHeight)
      }
    }
    else {
      scrollView.contentInset.bottom = 0
      keyboard.animate {
        self.randomView.transform = .identity
      }
    }
   
  }
}

Keyboard.swift

import UIKit
import NotificationCenter

protocol KeyboardObserverDelegate: class {
    func keyboardWillChange(_ keyboard: KeyboardNotification)
}

class KeyboardObserver: NSObject {
    
    weak var delegate: KeyboardObserverDelegate?
    
    override init() {
        super.init()
        
        NotificationCenter.default.addObserver(self, selector: #selector(handleNotification(_:)), name: UIApplication.keyboardWillChangeFrameNotification, object: nil)
    }
    
    @objc func handleNotification(_ notification: Notification) {
        guard let keyboardNotification = KeyboardNotification(notification) else {
            return
        }
        delegate?.keyboardWillChange(keyboardNotification)
    }
    
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
    
}

struct KeyboardNotification {
    
    let duration: TimeInterval
    let animationCurve: UIView.AnimationOptions
    let willShow: Bool
    let endHeight: CGFloat
    
    init?(_ notification: Notification) {
        guard let userInfo = notification.userInfo,
            let startFrame = (userInfo[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue,
            let endFrame = (userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue,
            let animationCurveRawNSN = userInfo[UIResponder.keyboardAnimationCurveUserInfoKey] as? NSNumber,
            let duration:TimeInterval = (userInfo[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber)?.doubleValue else { return nil }
        
        self.duration = duration
        
        let animationCurveRaw = animationCurveRawNSN.uintValue
        self.animationCurve = UIView.AnimationOptions(rawValue: animationCurveRaw)
        self.willShow = endFrame.origin.y < UIScreen.main.bounds.height
        self.endHeight = endFrame.height
    }
    
    func animate(animations: @escaping () -> Void) {
        animate(animations: animations, completion: nil)
    }
    
    func animate(animations: @escaping () -> Void, completion: ((Bool) -> Void)?) {
        UIView.animate(
            withDuration: duration,
            delay: 0.0,
            options: animationCurve,
            animations: animations,
            completion: completion
        )
    }
}