title: iOS 5 custom tab bar image vertical alignment
body: <p>I'm getting some odd behaviour with my custom tab bar. The images seem to be aligned incorrectly. Here is a screenshot (I have removed my own tab bar background to highlight my problem):</p>
  
  <p><img src="https://i.stack.imgur.com/u0EAq.png" alt="screenshot"></p>
  
  <p>Here is the code I'm using to set the images for each state:</p>
  
  <pre><code>self.tabBarController = [[[UITabBarController alloc] init] autorelease];
  self.tabBarController.viewControllers = [NSArray arrayWithObjects:homeNavController, whatsOnNavController, mapNavController, infoNavController, nil];
  self.tabBarController.delegate = self;
  
  // For iOS 5 only - custom tabs
  if ([self.tabBarController.tabBar respondsToSelector:@selector(selectedImageTintColor)]) 
  {
  
      // Set the background images
      //[[UITabBar appearance] setBackgroundImage: [UIImage imageNamed:@"nav_bg.png"]];
      [[UITabBar appearance] setSelectionIndicatorImage:[UIImage imageNamed:@"nav_over.png"]];
  
      [homeNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_home_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_home"]];
      [whatsOnNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_whats_on_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_whats_on"]];
      [mapNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_map_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_map"]];
      [infoNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_info_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_info"]];
  
  }
  </code></pre>
  
  <p>All of my replacement tab images are correctly sized (49 pixels high and 80 pixels wide for the non-retina versions).</p>
  
  <p>What could be causing this odd behaviour?</p>
  
  <h1>--- Update ---</h1>
  
  <p>Here is an updated screenshot with the background in place:</p>
  
  <p><img src="https://i.stack.imgur.com/FWtf6.png" alt="screenshot 2"></p>