iOS UIVisualEffectView 用在cell上面

底部是一个imageView
UIBlurEffect *blur = [UIBlurEffect effectWithStyle:UIBlurEffectStyleLight];
UIVisualEffectView *effectview = [[UIVisualEffectView alloc] initWithEffect:blur];

使用 imageWithUIView 进行获取图片就不会出现闪动（前提要设置 ： imageView.contentMode = UIViewContentModeScaleAspectFill ）

// 图片裁剪
            UIImageView *imageView = [UIImageView new];
            imageView.bounds = self.iconBGImageView.bounds;
            imageView.center = CGPointMake(-1000, 0);
            [self addSubview:imageView];
            imageView.image = image;
            imageView.contentMode = UIViewContentModeScaleAspectFill;
            imageView.clipsToBounds = YES;

            UIImage *image2 = [self imageWithUIView:imageView];
            [imageView removeFromSuperview];
            self.iconBGImageView.image = [self changeImage:image];
            self.iconBGImageView.contentMode = UIViewContentModeScaleAspectFill;
            self.iconBGImageView.clipsToBounds = YES;

• (UIImage) imageWithUIView:(UIView) view{
  // 创建一个bitmap的context
  // 并把它设置成为当前正在使用的context
  UIGraphicsBeginImageContext(view.bounds.size);
  CGContextRef currnetContext = UIGraphicsGetCurrentContext();
  [view.layer renderInContext:currnetContext];
  // 从当前context中创建一个改变大小后的图片
  UIImage* image = UIGraphicsGetImageFromCurrentImageContext();
  // 使当前的context出堆栈
  UIGraphicsEndImageContext();
  return image;
  }

• (UIImage *)changeImage:(UIImage *)image {
  UIGraphicsBeginImageContext(self.iconBGImageView.size);
  CGRect rect = self.iconBGImageView.bounds;
  [image drawInRect:rect];
  使用下面的就可以
  // [image drawInRect:rect withContentMode:UIViewContentModeScaleAspectFill clipsToBounds:YES];
  UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  // 拉伸不变形
  UIImage *networkImage = [newImage stretchableImageWithLeftCapWidth:newImage.size.width * 0.5
  topCapHeight:0];
  UIGraphicsEndImageContext();
  return newImage;
  }

解决思路： 将图片平铺处理，不能压缩。就可以 UIViewContentModeScaleAspectFill