iOS 8之后新添加了UIBlurEffect 类和 UIVisualEffectView 类来实现毛玻璃磨砂特效。
UIBlurEffect *blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
UIVisualEffectView *effectview = [[UIVisualEffectView alloc] initWithEffect:blur];
effectview.frame = self.view.bounds;
[self.view addSubview:effectview];
毛玻璃特效类型：
UIBlurEffectStyleExtraLight
UIBlurEffectStyleLight
UIBlurEffectStyleDark
分别如下：
UIBlurEffectStyleExtraLight
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UIBlurEffectStyleLight
131546495462_.pic_hd.jpg
UIBlurEffectStyleDark
151546495464_.pic_hd.jpg
