add bar button on keyboard

UITextField+BarButton.swift

extension UITextField {
    func addDoneButtonOnKeyboard(actionBefore: Selector, actionNext: Selector, actionDone: Selector) {
        guard let windowFrame = UIApplication.shared.keyWindow?.frame else {
            return
        }
        let keyToolbar = UIToolbar(frame: CGRect(origin: .zero, size: CGSize(width: windowFrame.width, height: 45)))
        keyToolbar.barStyle = .default
        let flexSpace = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
        let next = UIBarButtonItem(title: "próximo", style: .plain, target: nil, action: actionNext)
        let before = UIBarButtonItem(title: "anterior", style: .plain, target: nil, action: actionBefore)
        let done = UIBarButtonItem(title: "Ok", style: .done, target: nil, action: actionDone)
        var items = [UIBarButtonItem]()
        items.append(before)
        items.append(next)
        items.append(flexSpace)
        items.append(done)
        keyToolbar.items = items
        keyToolbar.sizeToFit()
        self.inputAccessoryView = keyToolbar
    }
}