【iOS开发】快速生成高斯模糊效果背景

//创建毛玻璃效果的背景
func createFrostBackground (img:UIImage,view:UIView) {
    let w = self.view.frame.width
    let h = self.view.frame.height
    let blurImageView = UIImageView(frame: CGRectMake(-w/2, -h/2, 2*w, 2*h)) //模糊背景是界面的4倍大小
    blurImageView.contentMode = UIViewContentMode.ScaleAspectFill
    blurImageView.image = img
    //创建毛玻璃效果层
    let visualEffectView = UIVisualEffectView(effect: UIBlurEffect(style: UIBlurEffectStyle.Light)) as UIVisualEffectView
    visualEffectView.frame = blurImageView.frame
    //添加毛玻璃效果层
    blurImageView.addSubview(visualEffectView)
    self.view.insertSubview(blurImageView, belowSubview: view)
}