IOS8模糊毛玻璃的效果UIVisualEffectView

UIVisualEffectView实现两种模糊效果：UIBlurEffect 和 UIVibrancyEffect

两者都是继承自UIView，前者放在任意的View里边都能对下册的视图渲染出模糊效果，后者是在前者的基础上对毛玻璃效果上层的视图做出高亮突出处理

代码如下：

@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")
    }

运行之后的效果：

点击“改变底图按钮”背景切换成另外一张图，模糊效果及时更新：

效果相当的酷