Add done button to Numeric Keypad

addDone.swift

    @IBOutlet weak var numberTextField: UITextField! 
    @IBOutlet weak var numberTextField2: UITextField!
    //Assumes that the tag's of the views are sequential

    override func viewDidLoad() {
        numberTextField.tag = 1
        numberTextField.tag = 2
        addDoneButtonTo(numberTextField)
        addDoneButtonTo(numberTextField2)
    }
    
    private func addDoneButtonTo(textField: UITextField) {
        let flexBarButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)
        let doneBarButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.Done, target: self, action: "didTapDone:")
        doneBarButton.tag = textField.tag + 1000
        let keyboardToolbar = UIToolbar()
        keyboardToolbar.sizeToFit()
        keyboardToolbar.items = [flexBarButton, doneBarButton]
        textField.inputAccessoryView = keyboardToolbar
    }

    func didTapDone(sender: UIBarButtonItem?) {
        if let senderView = sender {
            let nextTage=senderView.tag-1000+1;
            let nextResponder=self.view.viewWithTag(nextTage) as UIResponder!
            if (nextResponder != nil){
                nextResponder?.becomeFirstResponder()
            } else {
                let currentResponder=self.view.viewWithTag(senderView.tag-1000) as! UITextField!
                currentResponder.endEditing(true)
            }
        }
    }