[UIKit] BottomButton Keyboard + Combine + SnapKit

import SnapKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        hideKeyboardWhenTappedAround()
        NotificationCenter.default.publisher(for: UIResponder.keyboardWillShowNotification)
            .receive(on: DispatchQueue.main)
            .sink { notification in
                let info = notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue
                let keyboardHeight = info?.cgRectValue.height
                guard let keyboardHeight else { return }
                self.button.snp.remakeConstraints {
                    $0.height.equalTo(60)
                    $0.bottom.equalToSuperview().offset(-keyboardHeight)
                    $0.width.equalToSuperview()
                    $0.centerX.equalToSuperview()
                }
                UIView.animate(withDuration: 0.3) {
                    self.view.layoutIfNeeded()
                }
            }.store(in: &cancellables)
        
        NotificationCenter.default.publisher(for: UIResponder.keyboardWillHideNotification)
            .receive(on: DispatchQueue.main)
            .sink { _ in
                self.button.snp.remakeConstraints {
                    $0.height.equalTo(100)
                    $0.bottom.equalToSuperview()
                    $0.width.equalToSuperview()
                    $0.centerX.equalToSuperview()
                }
                UIView.animate(withDuration: 0.3) {
                    self.view.layoutIfNeeded()
                }
            }.store(in: &cancellables)
    }
}   
    
extension UIViewController {
    
    func hideKeyboardWhenTappedAround() {
        let tap = UITapGestureRecognizer(target: self, action: #selector(UIViewController.dismissKeyboard))
        tap.cancelsTouchesInView = false
        view.addGestureRecognizer(tap)
    }
    
    @objc func dismissKeyboard() {
        view.endEditing(true)
    }
}