自定义标签栏按钮在推送时不隐藏

Question

我有5个标签，中心按钮是自定义的，所以我创建了一个UITabBarController类来自定义中心按钮。发生的事情是当我 hidesBottomBarWhenPushed 标签栏变为隐藏时，除了中心自定义按钮仍然可见＆amp;甚至没有禁用当我选中

class TabBar: UITabBarController {

    @IBOutlet weak var centerButton:UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()

        let nImage = UIImage(named: "infobutton")
        let bImage = UIImageView(image: nImage!)
        bImage.frame.size = CGSize(width: 50, height: 50)


        let cButton: UIButton = UIButton.buttonWithType(UIButtonType.Custom) as UIButton
        cButton.autoresizingMask = UIViewAutoresizing.FlexibleRightMargin | UIViewAutoresizing.FlexibleLeftMargin | UIViewAutoresizing.FlexibleTopMargin | UIViewAutoresizing.FlexibleBottomMargin
        cButton.frame = CGRectMake(0,0, 50, 50)
        cButton.setBackgroundImage(nImage, forState: UIControlState.Normal)
        cButton.setBackgroundImage(nImage, forState: UIControlState.Highlighted)

        cButton.addTarget(self, action: "buttonPressed:", forControlEvents: UIControlEvents.TouchUpInside)
        self.centerButton = cButton

        var heightDifference:CGFloat = bImage.frame.size.height - self.tabBar.frame.size.height
        if (heightDifference < 0) {
            cButton.center = self.tabBar.center;
        } else {
            var center:CGPoint = self.tabBar.center;
            center.y = center.y - heightDifference/2.0;
            cButton.center = center
          }
        self.view.addSubview(cButton)

    }

    func buttonPressed(sender:UIButton) {
        self.selectedIndex = 2
    }
}