ios - 在Objective C中，我们如何将脸部模糊成圆形/圆形？

Question

我正在开发 iOS 应用程序，在该应用程序中我从图像中检测面部并模糊面部，我已经实现了矩形形式的模糊面部，但我需要的是模糊圆形面部。我这样做的目的是

-(void)markAfterFaceDetect:(NSArray *)features
{

    for (CIFaceFeature *f in features)
    {

        CGRect aRect = f.bounds;

        NSLog(@"here is the height of h %f",aRect.size.height);

        // aRect.size.height=aRect.size.height+10;

        aRect.origin.y = self.viewShow.bounds.size.height - aRect.size.height - aRect.origin.y;



        NSLog(@"Height Of the Image Is : == %f",_imageView.image.size.height);
        //self.bounds.size

        rectFaceDetect = aRect;



        UIVisualEffect *blurEffect;
        blurEffect = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];

        UIVisualEffectView *visualEffectView;
        visualEffectView = [[UIVisualEffectView alloc] initWithEffect:blurEffect];

        visualEffectView.frame = vv.frame;

        //visualEffectView.layer.cornerRadius = visualEffectView.frame.size.height/2;

        visualEffectView.alpha =0.96;

        visualEffectView.tag = markViewTag;
        // [self.imageView addSubview:visualEffectView];


        CAShapeLayer *mask = [CAShapeLayer layer];
        mask.path = [UIBezierPath bezierPathWithOvalInRect:visualEffectView.bounds].CGPath;
        visualEffectView.layer.mask = mask;
    }
}

使用这种方式，我设法以圆形或圆形模糊面部，但是当我截取视图以将模糊图像保存在应用程序数据库中时，它的 Alpha 变为 0 并且模糊区域变得可见，我用于截取屏幕截图的代码是

CGRect rect = viewShow.frame;
UIGraphicsBeginImageContext(rect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
[viewShow.layer renderInContext:context];
UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

这是屏幕截图之前和之后的图像应用模糊效果后截屏后 Alpha 变为 0