title: scrollView is nil when called from viewdidload
body: <p>I want to scrolling view when navigationItem clicked.
  But..here is some error.</p>
  
  <ol>
  <li><p>I want to make snapchatlike scroll view.
  It works fine, but... when I call scrollView out of viewdidload function, scrollView is nil!</p></li>
  <li><p>I already make snapchat like swipe view. but I want to make swipe view when navigation Item(heart mark) clicked. </p></li>
  </ol>
  
  <p>My ViewController viewdidload func - it works fine</p>
  
  <pre><code>@IBOutlet weak var scrollView: UIScrollView!
  
  
  var V1 : LeftViewController = LeftViewController(nibName: "LeftViewController", bundle: nil)
  var V2 : CenterViewController = CenterViewController(nibName: "CenterViewController", bundle: nil)
  var V3 : RightViewController = RightViewController(nibName: "RightViewController", bundle: nil)
  
  
  
  override func viewDidLoad() {
  
      super.viewDidLoad()
  
  
  
      self.addChildViewController(V1)
      self.scrollView.addSubview(V1.view)
      V1.didMoveToParentViewController(self)
  
      self.addChildViewController(V2)
      self.scrollView.addSubview(V2.view)
      V2.didMoveToParentViewController(self)
  
      self.addChildViewController(V3)
      self.scrollView.addSubview(V3.view)
      V3.didMoveToParentViewController(self)
  
      var V2Frame : CGRect = V2.view.frame
      V2Frame.origin.x = self.view.frame.width
      V2.view.frame = V2Frame
  
  
      var V3Frame : CGRect = V3.view.frame
      V3Frame.origin.x = 2 * self.view.frame.width
      V3.view.frame = V3Frame
  
      println(self)
      println(scrollView)
      println(V2.view.frame)
  
      self.scrollView.setContentOffset(CGPointMake(V2Frame.origin.x, self.view.frame.size.height), animated: false)
  
  
  
      self.scrollView.contentSize = CGSizeMake(self.view.frame.width * 3, self.view.frame.size.height)        }
  </code></pre>
  
  <p>My ViewController clickEvent func - why scrollView is nil?</p>
  
  <pre><code>    func clickEvent() {
  
      self.scrollView?.scrollRectToVisible(V2.view.frame, animated: true)
  
      println(self)
      println(scrollView)
      println(V2.view.frame)
      //self.scrollView.setContentOffset(CGPointMake(V2.view.frame.origin.x, self.view.frame.size.height), animated: true)
  }
  </code></pre>
  
  <p>I call clickEvent in Viewcontroller from other CenterViewController
  - it can call fine but...in ViewController clickEvent functions' scrollView is nil.. How can I fix it?</p>
  
  <pre><code>func clickEvent(sender: AnyObject) {
  
     ViewController().clickEvent()
  }
  </code></pre>