iOS系统自带毛玻璃效果

UIImageView * imageview = [[ UIImageView alloc ] initWithImage :[ UIImage imageNamed : @" 屏幕快照 2015-12-18 下午 10.51.33" ]];

    imageview. userInteractionEnabled = YES ;

    imageview. contentMode = UIViewContentModeScaleAspectFit ;

    imageview. frame = CGRectMake ( 0 , 0 , 375 , 668 );

    [ self . view addSubview :imageview];

    UIBlurEffect * blur = [ UIBlurEffect effectWithStyle : UIBlurEffectStyleDark ];

    UIVisualEffectView * effectview = [[ UIVisualEffectView alloc ] initWithEffect :blur];

    effectview. frame = CGRectMake ( 0 , 0 , imageview. frame . size . width , imageview. frame . size . height );

    [imageview addSubview :effectview];

    UIButton *button = [ UIButton buttonWithType : UIButtonTypeSystem ];

    button. frame = CGRectMake ( 10 , 50 , 60 , 60 );

    [button setTitle : @"btn" forState : UIControlStateNormal ];     [effectview.contentView addSubview:button];