title: Unable to embed second view controller on top of first view controller
body: <p>Im using the following code to show first view controller on top of a second view controller just like a dialog.</p>
  
  <pre><code>    [self addChildViewController:viewController];
  viewController.view.frame = self.view.frame;
  [self.view addSubview:viewController.view];
  viewController.view.alpha = 0;
  [viewController didMoveToParentViewController:self];
  
  [UIView animateWithDuration:0.25 delay:0.0 options:UIViewAnimationOptionCurveLinear animations:^
   {
       viewController.view.alpha = 1;
   }
                   completion:nil];
  </code></pre>
  
  <p>But the second view controller is not visible...How can I be able to sort this out?</p>