IOS8模糊毛玻璃的效果UIVisualEffectView

 @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")
    }