Make a UIBarButtonItem disappear using swift IOS

Use the property enabled and tintColor

    let barButtonItem:UIBarButtonItem? = nil

    if isHidden{
        barButtonItem?.enabled      = false
        barButtonItem?.tintColor    = UIColor.clearColor()
    }else{
        barButtonItem?.enabled      = true
        barButtonItem?.tintColor    = nil
    }