图片旋转锯齿

    //在图片边缘添加一个像素的透明区域，去图片锯齿

    CGRect imageRrect = CGRectMake(0, 0,imageView.frame.size.width, imageView.frame.size.height);

    UIGraphicsBeginImageContext(imageRrect.size); 

    [imageView.imagedrawInRect:CGRectMake(1,1,imageView.frame.size.width-2,imageView.frame.size.height-2)];

    imageView.image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

 

 

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消除锯齿：
        imageView.layer.shadowOffset = CGSizeMake(0, 2);//0,2
        imageView.layer.shadowRadius = 2.0;
        imageView.layer.shadowColor = [UIColor whiteColor].CGColor;
        imageView.layer.shadowOpacity = 0.8;
        imageView.layer.borderColor = [UIColor whiteColor].CGColor;
        imageView.layer.borderWidth = 3.0;//2.0
        imageView.layer.cornerRadius = 3.0;//3.0
        imageView.layer.masksToBounds=YES; 
        [imageView.layer setShouldRasterize:YES];