@IBOutlet weak var imageView: UIImageView!

override func viewDidLoad() {

        super.viewDidLoad()

        var blurEffect = UIBlurEffect(style: UIBlurEffectStyle.Light)

        var blurEffectView = UIVisualEffectView(effect: blurEffect)

        blurEffectView.frame = view.frame

        view.addSubview(blurEffectView)

        var vibrancyEffect = UIVibrancyEffect(forBlurEffect: blurEffect)

        var vibrancyEffectView = UIVisualEffectView(effect: vibrancyEffect)

        vibrancyEffectView.frame = view.frame

        var label = UILabel()

        label.text = "Vibrant Label!!!"

        label.font = UIFont.systemFontOfSize(72.0)

        label.sizeToFit()

        label.center = view.center

        vibrancyEffectView.contentView.addSubview(label)

        blurEffectView.contentView.addSubview(vibrancyEffectView)

        var btn = UIButton(frame: CGRect(x: 300, y: 450, width: 300, height: 100))

        btn.setTitle("改变底图", forState: UIControlState.Normal)

        btn.addTarget(self, action: "updateBackImage:", forControlEvents: UIControlEvents.TouchUpInside)

        vibrancyEffectView.contentView.addSubview(btn)

    }

func updateBackImage(sender: AnyObject) {

        imageView.image = UIImage(named: "z")

    }