title: UIPAGEVIEWCONTROLLER Datasource methods called Twice on Fast Swipe
body: <p>I am trying to implement the basic <code>UIPageviewController</code> Example.But when I swipe fastly in right/left direction, the datasource method <code>viewcontrollerAfterViewController</code> is getting called twice.It is happening in ios 7 only. Any body knows why this happens?</p>