iOS BUG UIView转UIImage模糊失真

##UIView转成Image

- (UIImage *)capture {
    UIGraphicsBeginImageContextWithOptions(self.bounds.size, YES, 0.0);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return img;
}

运行后发现，转换后的UIImage显示后会变模糊失真

##解决方案

- (UIImage *)capture {
    CGSize s = self .bounds.size;
    // 下面方法，第一个参数表示区域大小。第二个参数表示是否是非透明的。如果需要显示半透明效果，需要传NO，否则传YES。第三个参数就是屏幕密度了
    UIGraphicsBeginImageContextWithOptions(s, NO, [UIScreen mainScreen].scale);
    [self.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage*image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

##UIScrollView内容转成UIIMageView方法

- (UIImage *)captureScrollView:(UIScrollView *)scrollView
{
    UIImage* image = nil;
    UIGraphicsBeginImageContextWithOptions(scrollView.contentSize, NO, 0.0);
    {
        CGPoint savedContentOffset = scrollView.contentOffset;
        CGRect savedFrame = scrollView.frame;
        scrollView.contentOffset = CGPointZero;
        scrollView.frame = CGRectMake(0, 0, scrollView.contentSize.width, scrollView.contentSize.height);
        
        [scrollView.layer renderInContext: UIGraphicsGetCurrentContext()];
        image = UIGraphicsGetImageFromCurrentImageContext();
        
        scrollView.contentOffset = savedContentOffset;
        scrollView.frame = savedFrame;
    }
    UIGraphicsEndImageContext();
    
    if (image != nil) {
        return image;
    }
    return nil;
}

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