title: raised tab bar and dismissModalViewControllerAnimated
body: <p>I created an app with raised Tab Bar like that we see in applications such as Foursquare, Instagram or DailyBooth. To do that I put a UIButton at the center of the Tab Bar and everything seems OK, here the code in my AppDelegate:</p>
  
  <pre><code>- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  
   self.mainButton = [UIButton buttonWithType:UIButtonTypeCustom];
      // set up the mainButton with an image and calculate coordinates
  
  [self.mainButton addTarget:self action:@selector(showMainViewController:) forControlEvents:UIControlEventTouchUpInside];
  
      [self.window addSubview:tabBarController.view];
      [self.window addSubview:mainButton];
      [self.window makeKeyAndVisible];
  }
  </code></pre>
  
  <p>The mainButton has been defined in AppDelegate.h with its property (non atomic, retain) and synthesized.</p>
  
  <p>By pushing the mainButton:</p>
  
  <pre><code>- (IBAction) showMainViewController:(id)sender {
      [self.mainButton setHidden:YES];
      MainViewController *mainVC = [[MainViewController alloc] initWithNibName:@"MainViewController" bundle:nil];
      UINavigationController *nc = [[UINavigationController alloc] initWithRootViewController:mainVC];
      [self.mainNavController presentModalViewController:nc animated:YES];
      [nc release];
      [mainVC release];
  }
  </code></pre>
  
  <p>Since the mainButton remain diplayed I decided to hide it.</p>
  
  <p>At this point I have a doubt: I have to avoid hiding the button?</p>
  
  <p>Problems comes when I decide to dismiss the MainViewController, I don't know if I'm working properly, I'm doing it by a simple <code>[self dismissModalViewControllerAnimated:YES];</code> in MainViewController.m
  The result is that I'm not abled to unhide the mainButton by something like <code>[self.mainButton setHidden:NO];</code></p>