How to update UIWebView during an animation?
- (IBAction)flipWebViewGestureRecognizer:(id)sender
{
    // isFrontView is boolean to determine if card is front or back
    if(self.isFrontOfView)
    {
        self.isFrontOfView = NO;
        [UIView transitionWithView: self.imageView
                          duration: 1.0
                           options: UIViewAnimationOptionTransitionFlipFromTop
                        animations: ^{ [self loadBack]; }
                        completion: nil];
    }
    else
    {
        self.isFrontOfView = YES;
        [UIView transitionWithView: self.imageView
                          duration: 1.0
                           options: UIViewAnimationOptionTransitionFlipFromTop
                        animations: ^{ [self loadFront]; }
                        completion: nil];
    }
}

- (void) loadFront
{
    NSString *html = @"<p>Front Of Card</p>";
    [self.viewWebView loadHTMLString:html baseURL:nil];
}

- (void) loadBack
{
    NSString *html = @"<p>Front Of Card</p> <br /> <p>as well as back of card<p>";
    [self.viewWebView loadHTMLString:html baseURL:nil];
}