title: Swift: How to make a scroll view execute child view controllers viewDidLoad
body: <p>I have a main menu view controller which hosts a scroll view containing 4 different child view controllers which are selected using XLPagerTabStrip (effectively a tab bar). The viewDidLoad of each child controller is only executed the first time one of the child view controllers is loaded within the main menu, but I want it to execute every time each child view controller is loaded.</p>
  
  <p>Code that instantiates the view controllers within the main menu:</p>
  
  <pre><code>let storyboard = UIStoryboard(name: "Main", bundle: nil)
  let childOneVC = storyboard.instantiateViewControllerWithIdentifier("childOne")
  </code></pre>