title: How to write code on a tab bar controller created by storyboard？
body: <p>I am new to objective-c and Xcode. As far as I know, the way of coding on a view controller created by storyboard, is to create a custom subclass of UIViewController ,connect it to the VC and make outlets or actions.</p>
  
  <p>When it comes to a tab bar controller or a navigation controller, I wonder how to program on these controllers. For example: I drag a tab bar controller on to storyboard and want to set the <strong>selected images</strong> of the tab bar items, which (I was told) can't be set by storyboard attributes inspector, I need to use the <em>initWithTitle:image:selectedImage:</em> method by code.
  So my question is : where should I put the <em>initWithTitle:image:selectedImage:</em> ? Should I create a custom subclass of UITabBarController, make outlet on the subclass file and program in the file? Or there're other easy ways instead? (Someone told me to code in AppDelegate file, but I failed. If it is the right way, please tell me more detail.)</p>
  
  <p>Thanks.</p>