title: how does LaunchScreen.storyboard redirect to Main.storyboard
body: <p>I'm newbie of iOS developer, and I know that is very simple question but I really can't understand reason.</p>
  
  <p>when I build <code>SingleViewApplication</code>, Xcode auto generate <code>LaunchScreen.storyboard</code> and <code>Main.storyboard</code>,</p>
  
  <p>but I can't find any code like <code>[self.navigationController pushViewController:]</code> which may choose that what view controller enter stack as last one of top-level view,</p>
  
  <p>I only find <code>ViewController.{h,m}</code> as first and see no logic that change view from <code>LaunchScreen.storyboard</code> to <code>Main.storyboard</code>.</p>
  
  <p>could anyone help? thanks..</p>