KeyboardObserving.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import PlaygroundSupport

final class MyViewController: UIViewController {
    
    override func loadView() {
        let view = UIView()
        view.backgroundColor = .white
        
        // Add UITextField
        let textField = UITextField()
        textField.frame = CGRect(x: 150, y: 200, width: 200, height: 20)
        textField.placeholder = "Tap to show keyboard"
        textField.textColor = .black
        view.addSubview(textField)
        
        self.view = view
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Add UIButton
        let button = UIButton(type: .custom)
        button.frame = CGRect(x: 0, y: 0, width: 200, height: 20)
        button.setTitle("Tap to hide keyboard", for: UIControl.State())
        button.setTitleColor(.red, for: UIControl.State())
        button.addTarget(self.view,
                         action: #selector(UIView.endEditing(_:)),
                         for: .touchUpInside)
        view.addSubview(button)
        
        // Setup observing
        let notificationCenter = NotificationCenter.default
        notificationCenter.addObserver(self,
                                       selector: #selector(keyboardWillShow(_:)),
                                       name: UIApplication.keyboardWillShowNotification, object: nil)
        notificationCenter.addObserver(self,
                                       selector: #selector(keyboardWillHide(_:)),
                                       name: UIApplication.keyboardWillHideNotification, object: nil)
    }
    
    @objc private func keyboardWillShow(_ notification: Notification) {
        print("keyboardWillShow: \(String(describing: notification.userInfo))")
    }
    
    @objc private func keyboardWillHide(_ notification: Notification) {
        print("keyboardWillHide: \(String(describing: notification.userInfo))")
    }
    
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()