title: How to present a view controller from tab bar button
body: <p>I have a tab bar controller with 3 tab bar buttons.  At the moment it looks like this:</p>
  
  <pre><code>class CustomTabBarController: UITabBarController {
  
  override func viewDidLoad() {
      super.viewDidLoad()
  
      let firstTabBarController = FirstController()
      let firstTabBarNavigationController = UINavigationController(rootViewController: firstTabBarController)
      firstTabBarNavigationController.tabBarItem.title = "First Tab"
  
      let secondTabBarController = SecondController()
      let secondTabBarNavigationController = UINavigationController(rootViewController: secondTabBarController)
      secondTabBarController.tabBarItem.title = "Second Tab"
  
      let thirdTabBarController = ThirdController()
      let thirdTabBarNavigationController = UINavigationController(rootViewController: thirdTabBarController)
      thirdTabBarNavigationController.tabBarItem.title = "Third Tab"
  
      viewControllers = [firstTabBarNavigationController, secondTabBarNavigationController, thirdTabBarNavigationController]
  
  }
  }
  </code></pre>
  
  <p>Right now, with the code above, all the view controllers are sitting inside the <code>CustomTabBarController</code></p>
  
  <p>I want the the middle tab bar button, the <code>secondTabBarNavigationController</code> to present a view controller, specifically the <code>UIImagePickerController</code> for a user to select an image, similar to Instagram.</p>
  
  <p>How can this be achieved? I am not using storyboards</p>