title: view.frame.size.height changing in UIViewController
body: <p>Inside my view, I have a table and an ad banner, all of which are created through Interface Builder. But I noticed that my view.frame.size.height seems to change through the course of execution of my app even though I haven't changed the size.</p>
  
  <p>Can someone explain to me why this is happening?</p>
  
  <p>What I'm doing is moving the ad banner off screen on viewDidLoad, at which point, if I print out self.view.frame.size.height, the value is: 460.00. At this time, I am also increasing the tableView's size so it takes up the space the adBanner once occupied and moving the adBanner off-screen at the same time.</p>
  
  <p>Then later on when I get the bannerViewDidLoadAd message, I once again print out the self.view.frame.size.height, at which point it is 367.00. I don't understand why the view's size has changed.</p>
  
  <pre><code>- (void)moveAdvertOffScreen
  {
      // Make the table view take up the void left by the banner (320x50 block)
  
      CGRect originalTableFrame = self.tableView.frame;
      CGFloat newTableHeight = self.view.frame.size.height;
  
      CGRect newTableFrame = originalTableFrame;
      newTableFrame.size.height = newTableHeight;
  
      // Position the banner below the table view (offscreen)
      CGRect newBannerFrame = self.adBannerView.frame;
      newBannerFrame.origin.y = newTableHeight;
  
      self.tableView.frame = newTableFrame;   
      self.adBannerView.frame = newBannerFrame;    
  }
  
  - (void)moveAdvertOnScreen
  {
      CGRect newBannerFrame = self.adBannerView.frame;    
      newBannerFrame.origin.y = self.view.frame.size.height - newBannerFrame.size.height;
  
      CGRect originalTableFrame = self.tableView.frame;
      CGFloat newTableHeight = self.view.frame.size.height - newBannerFrame.size.height;
  
      CGRect newTableFrame = originalTableFrame;
      newTableFrame.size.height = newTableHeight;
  
      [UIView beginAnimations:@"BannerViewIntro" context:NULL];
      self.tableView.frame = newTableFrame;
      self.adBannerView.frame = newBannerFrame;
      [UIView commitAnimations];  
  }
  </code></pre>