iOS端毛玻璃效果大致有以下四种方式
1.UIToolbar 7.0之前
2.UIBlurEffect 8.0开发的接口
3.CoreImage框架下CIFilter滤镜来做
4. 通过Accelerate.framework框架计算RGB色滴值的方式

1.UIToolbar

    UIToolbar *toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0,0,backview.frame.size.width,backview.frame.size.height)];
      /*
       UIBarStyleDefault 灰白色
       UIBarStyleBlack 纯黑色 不设置透明度看不见
       UIBarStyleBlackOpaque 纯黑色
       UIBarStyleBlackTranslucent 纯黑色
       */
    toolbar.barStyle = UIBarStyleBlackTranslucent;
    toolbar.alpha = 0.67;
    [backview addSubview:toolbar];
    

无论是灰白还是纯黑效果都不佳。

2.UIBlurEffect

   UIBlurEffect *blureffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleDark];

    UIVisualEffectView *effectview = [[UIVisualEffectView alloc]initWithEffect:blureffect];
    effectview.frame = CGRectMake(0,0,backview.frame.size.width,backview.frame.size.height);
    effectview.alpha = 0.7f;
    [backview addSubview:effectview];

3.CoreImage

   获取上下文
    CIContext *context = [CIContext contextWithOptions:nil];
    //把uiimage转换成CIImage
    CIImage *ciImage = [CIImage imageWithCGImage:[UIImage imageNamed:@"timg-2.jpeg"].CGImage];
    //滤镜
    /*
     CIBoxBlur,**
     **    CIDiscBlur,**
     **    CIGaussianBlur,**
     **    CIMaskedVariableBlur,**
     **    CIMedianFilter,**
     **    CIMotionBlur,**
     **    CINoiseReduction,**
     **    CIZoomBlur**

     */
    CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
    //设置输入属性InputImage
    [filter setValue:ciImage forKey:kCIInputImageKey];
    //设置模糊程度inputRadius
    [filter setValue:@(5) forKey: @"inputRadius"];
    //设置输出属性
    CIImage *result = [filter valueForKey:kCIOutputImageKey];
    //将加过滤镜的图片输出
    CGImageRef outImage = [context createCGImage: result fromRect:ciImage.extent];
    //转换成uiimage
    UIImage * blurImage = [UIImage imageWithCGImage:outImage];

    backview.image = blurImage;
    //
    CGImageRelease(outImage);

第四种方式
小马哥的第三方库MCBlur库就是通过计算的方式
MCBlur
有兴趣可以去看看