Old plain way of getting keyboard height vs RxKeyboard framework. Rx frameworks can be found here - https://github.com/RxSwiftCommunity/RxKeyboard

NativeKeyboardHeight_vs_RxKeyboard.swift

// native way
override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(
        self,
        selector: #selector(keyboardChangedFrame),
        name: UIResponder.keyboardDidChangeFrameNotification,
        object: nil
    )
}

@objc func keyboardChangedFrame(notification: Notification) {
    guard let keyboardFrame = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
    let keyboardHeight = keyboardFrame.cgRectValue.height
    scrollView.contentInset.bottom = keyboardHeight
}
//____________________//

// RxKeyboard
override func viewDidLoad() {
    super.viewDidLoad()
    RxKeyboard.instance.visibleHeight
        .drive(onNext: { [unowned self] in self.tableView.contentInset.bottom = $0 })
        .disposed(by: disposeBag)
}