UIWebView+Screenshot

UIWebView+Screenshot.m

- (void)viewDidLoad
{
    [super viewDidLoad];
  // Do any additional setup after loading the view, typically from a nib.
    [self.webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://stackoverflow.com/questions/10692221/screenshot-of-an-uiwebview-that-is-not-currently-on-screen"]]];
    NSLog(@"webview = %@",self.webView);
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)webViewDidFinishLoad:(UIWebView *)webView{
    NSLog(@"contentSize = %f %f",webView.scrollView.contentSize.width,webView.scrollView.contentSize.height);
    webView.frame = CGRectMake(0, 0, webView.scrollView.contentSize.width, webView.scrollView.contentSize.height);
    UIGraphicsBeginImageContextWithOptions(webView.scrollView.contentSize, NO, 0);
    [webView.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    NSData *data = UIImagePNGRepresentation(image);
    NSString *path = [NSTemporaryDirectory() stringByAppendingPathComponent:@"page.png"];
    [data writeToFile:path atomically:YES];
    NSLog(@"path = %@",path);
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error{
    NSLog(@"%s",__func__);
}

it's wrong,this will not work absolutely

After you take that, u could use "self.webView.scrollView.contentOffset = CGPointMake(0, currentOffset);" to scroll your webview down and take other one.