iphone 保存网页快照

- (void) save {
    UIGraphicsBeginImageContext(webView.frame.size); 
    [webView.layer renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    UIImageWriteToSavedPhotosAlbum(viewImage, nil, nil, nil);
    NSLog(@"TEST");
}