问使堆栈视图元素居中，而不填充它们

EN

func show(error: Bool, withMessage message : String? = nil, andRetryAction retry: (() -> Void)? = nil){
    if error{
        let iconLabel = UILabel()
        iconLabel.GMDIcon = .gmdErrorOutline
        iconLabel.textAlignment = .center
        iconLabel.numberOfLines = 0
        iconLabel.font = iconLabel.font.withSize(50)
        iconLabel.textColor = Constants.Colors.ErrorColor

        iconLabel.backgroundColor = .blue

        let messageLabel = UILabel()
        messageLabel.text = message ?? "Ocorreu um erro"
        messageLabel.textColor = Constants.Colors.ErrorColor
        messageLabel.numberOfLines = 0
        messageLabel.textAlignment = .center
        messageLabel.font = UIFont(name: "TrebuchetMS", size: 20)

        messageLabel.backgroundColor = .green

        var views: [UIView] = [iconLabel, messageLabel]

        if let retry = retry{
            let button = RaisedButton(title: "Tentar novamente")
            button.pulseColor = Constants.Colors.PrimaryTextColor
            button.backgroundColor = Constants.Colors.PrimaryColor
            button.titleColor = .white
            button.actionHandle(controlEvents: .touchUpInside, ForAction: retry)
            button.contentEdgeInsets = UIEdgeInsetsMake(10,10,10,10)


            views.append(button)
        }


    }else{
        self.backgroundView = nil
    }
}
let stack = UIStackView()
    stack.spacing = 10
    stack.axis = .vertical
    stack.alignment = .center
    stack.distribution = .fill
    stack.translatesAutoresizingMaskIntoConstraints = false


    for view in views{
        view.translatesAutoresizingMaskIntoConstraints = false
        stack.addArrangedSubview(view)
    }

    if self.tableFooterView == nil{
        tableFooterView = UIView()
    }
    self.backgroundView = stack;

    if #available(iOS 11, *) {
        let guide = self.safeAreaLayoutGuide

        stack.topAnchor.constraint(greaterThanOrEqualTo: guide.topAnchor).isActive = true
        stack.bottomAnchor.constraint(greaterThanOrEqualTo: guide.bottomAnchor).isActive = true
        stack.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
        stack.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
        stack.centerYAnchor.constraint(equalTo: guide.centerYAnchor).isActive = true
    } else {
        stack.topAnchor.constraint(greaterThanOrEqualTo: self.topAnchor).isActive = true
        stack.bottomAnchor.constraint(greaterThanOrEqualTo: self.bottomAnchor).isActive = true
        stack.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
        stack.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
        stack.centerYAnchor.constraint(equalTo: self.centerYAnchor).isActive = true
    }