title: Animating UIImageView flip from middle
body: <p>I'm trying for a while to build an ebook, flipping page (from left to right) and zooming.
  So far I've tested a few projects but none of them was good enough to do both.
  I've decided to build one of my own, so I started with basic flip animation like this:</p>
  
  <pre><code>- (void)viewDidLoad
  {
      [super viewDidLoad];
      // Do any additional setup after loading the view.
      self.scrollView.delegate = self;
      self.scrollView.maximumZoomScale = 5.0f;
  
      UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTap:)];
      tapGesture.delegate = self;
      tapGesture.numberOfTapsRequired = 1;
      tapGesture.numberOfTouchesRequired = 1;
      [self.scrollView addGestureRecognizer:tapGesture];
  }
  
  #pragma mark - UIScrollView Delegate
  
  - (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
  {
      return self.imageView;
  }
  
  #pragma mark - UIGestureRecognizer Delegate
  
  - (void)handleTap:(UITapGestureRecognizer *)tapGestur
  {
      NSLog(@"%s", __PRETTY_FUNCTION__);
  
      if (tapGestur.state == UIGestureRecognizerStateEnded) {
  
          [UIView transitionWithView:self.imageView duration:1 options:UIViewAnimationOptionTransitionFlipFromRight|UIViewAnimationOptionCurveEaseInOut animations:^{
              if (!flipped) {
                  self.imageView.image = [UIImage imageNamed:@"2-IPAD-P.jpg"];
                  flipped = YES;
              }
              else {
                  self.imageView.image = [UIImage imageNamed:@"1-IPAD-P.jpg"];
              }
          } completion:^(BOOL finished) {
              //
          }];
      }
  }
  </code></pre>
  
  <p>What I'm trying to do now is transition flipping page (left to right) from the middle of the image.
  Any idea how can I do this using UIVIew? Or maybe better options?</p>