[Keyboard Event With RxSwift] #iOS

ViewController.swift

import RxSwift
import RxCocoa

class ViewController: UIViewController {

    @IBOutlet private weak var bottomConstraint: NSLayoutConstraint!

    private let disposeBag = DisposeBag()

	override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.rx.notification(UIView.keyboardWillShowNotification)
            .subscribe(onNext: { notification in
                self.keyboardWillShow(notification)
            })
            .disposed(by: disposeBag)

        NotificationCenter.default.rx.notification(UIView.keyboardWillHideNotification)
            .subscribe(onNext: { notification in
                self.keyboardWillHide(notification)
            })
            .disposed(by: disposeBag)
    }

    // MARK: - keyboard event

    @objc private func keyboardWillShow(_ notification: Notification) {
        guard let userInfo = notification.userInfo as? [String: Any] else { return }
        guard let keyboardInfo = userInfo[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue else { return }
        let keyboardSize = keyboardInfo.cgRectValue.size
        var safeAreaBottom: CGFloat = 0
        if #available(iOS 11.0, *) {
            safeAreaBottom = self.view.safeAreaInsets.bottom
        }
        bottomConstraint.constant = keyboardSize.height - safeAreaBottom
    }

    @objc private func keyboardWillHide(_: Notification) {
        bottomConstraint.constant = 0
    }
}