- (UIImage *)cutPic{
    
    CGRect snapshotFrame = CGRectMake(0, 0, _webView.scrollView.contentSize.width, _webView.scrollView.contentSize.height);
    UIEdgeInsets snapshotEdgeInsets = UIEdgeInsetsZero;
    UIImage *shareImage = [self snapshotViewFromRect:snapshotFrame withCapInsets:snapshotEdgeInsets];
    NSString *path_document = NSHomeDirectory();
    //设置一个图片的存储路径
    NSString *imagePath = [path_document stringByAppendingString:@"/Documents/picc.png"];
    //把图片直接保存到指定的路径（同时应该把图片的路径imagePath存起来，下次就可以直接用来取）
    [UIImagePNGRepresentation(shareImage) writeToFile:imagePath atomically:YES];
    
    return shareImage;
}

或者保存到相册：
UIImageWriteToSavedPhotosAlbum(shareImage, self, @selector(completedWithImage:error:context:), NULL);

- (void)completedWithImage:(UIImage *)image error:(NSError *)error context:(void *)contextInfo{
    NSString *toast = (!image || error)? [NSString stringWithFormat:@"保存图片失败 , 错误：%@",error] : @"保存图片成功";
    [self.view makeToast:toast duration:2.0 position:CSToastPositionCenter];
}


***
// 网页长截图
- (UIImage *)snapshotViewFromRect:(CGRect)rect withCapInsets:(UIEdgeInsets)capInsets {
    
    CGFloat scale = [UIScreen mainScreen].scale;
    
    CGSize boundsSize = self.webView.bounds.size;
    CGFloat boundsWidth = boundsSize.width;
    CGFloat boundsHeight = boundsSize.height;
    
    CGSize contentSize = self.webView.scrollView.contentSize;
    CGFloat contentHeight = contentSize.height;
    //    CGFloat contentWidth = contentSize.width;
    
    CGPoint offset = self.webView.scrollView.contentOffset;
    
    [self.webView.scrollView setContentOffset:CGPointMake(0, 0)];
    
    NSMutableArray *images = [NSMutableArray array];
    while (contentHeight > 0) {
        UIGraphicsBeginImageContextWithOptions(boundsSize, NO, [UIScreen mainScreen].scale);
        [self.webView.layer renderInContext:UIGraphicsGetCurrentContext()];
        UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        [images addObject:image];
        
        CGFloat offsetY = self.webView.scrollView.contentOffset.y;
        [self.webView.scrollView setContentOffset:CGPointMake(0, offsetY + boundsHeight)];
        contentHeight -= boundsHeight;
    }
    
    
    [self.webView.scrollView setContentOffset:offset];
    
    CGSize imageSize = CGSizeMake(contentSize.width * scale,
                                  contentSize.height * scale);
    UIGraphicsBeginImageContext(imageSize);
    [images enumerateObjectsUsingBlock:^(UIImage *image, NSUInteger idx, BOOL *stop) {
        [image drawInRect:CGRectMake(0,
                                     scale * boundsHeight * idx,
                                     scale * boundsWidth,
                                     scale * boundsHeight)];
    }];
    UIImage *fullImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    UIImageView * snapshotView = [[UIImageView alloc]initWithFrame:CGRectMake(rect.origin.x, rect.origin.y, rect.size.width, rect.size.height)];
    
    snapshotView.image = [fullImage resizableImageWithCapInsets:capInsets];
    return snapshotView.image;
}