Centre UILabel dans le Milieu de la Barre d'outils sur un Clavier

Comment puis-je centre une étiquette dans le milieu du clavier de la barre d'outils? Je peux obtenir le label dans le milieu du clavier, mais il n'est pas centré correctement

lazy var textView: UITextView = {
    // ...
}()

lazy var dummyToolBarButton: UIButton = {
    let button = UIButton(type: .system)
    button.translatesAutoresizingMaskIntoConstraints = false
    button.setImage(UIImage(named: "cogIcon"), for: .normal)
    button.alpha = 0
    button.sizeToFit()
    return button
}()

lazy var timerLabel: UILabel = {
    let label = UILabel()
    label.translatesAutoresizingMaskIntoConstraints = false
    label.text = "00:00"
    label.font = UIFont.monospacedDigitSystemFont(ofSize: 15.5, weight: .regular)
    label.backgroundColor = .clear
    label.textColor = .gray
    label.textAlignment = .center
    label.sizeToFit()
    return label
}()

override func viewDidLoad() {
    super.viewDidLoad()

    setToolBarOnKeyboard()
}

func setToolBarOnKeyboard() {
    
    let toolBar = UIToolbar()
    toolBar.sizeToFit()
    
    let invisibleDummyButton = UIBarButtonItem(customView: dummyToolBarButton) // alpha is set to 0
    
    let flexibleSpaceLeft = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    
    let labelItem = UIBarButtonItem(customView: timerLabel)
    
    let flexibleSpaceRight = UIBarButtonItem(barButtonSystemItem: .flexibleSpace, target: nil, action: nil)
    
    let doneButton = UIBarButtonItem(barButtonSystemItem: .done, target: self, action: #selector(dismissKeyboard))
    
    toolBar.setItems([invisibleDummyButton, flexibleSpaceLeft, labelItem, flexibleSpaceRight, doneButton], animated: false)
    
    textView.inputAccessoryView = toolBar
}

@objc func dismissKeyboard() { }