title: Prevent UIPageViewController's swipe from affecting a UISlider
body: <p>I've seen this question asked in other areas but none of the answers work in my case.  I have a UIPageViewController that has a child view controller containing a UISlider.  </p>
  
  <p>When you go to try to move the slider, it activates the page view controller's scrolling instead.  You have to tap, pause on the slider circle, and then move.</p>
  
  <p>The UIPageViewController is set to the scroll type, and thus the gestureRecognizers are not set.  (The header states "Only populated if transition style is 'UIPageViewControllerTransitionStylePageCurl'").  Thus I can't even get proper access to the gestures.</p>
  
  <p>I've tried several things to prevent the UIPageViewController from affecting the slider, but to no avail.  I've tried:
  1) walking the child subtree and setting the UIScrollView's pan gesture delegate to myself (this causes a crash)
  2) Add my own gesture on top, and check the y value.  This will prevent the swipe, but it also eats the tap and move so the slider doesn't actually change as expected
  3) Implemented a custom slider with custom gestures.  The problem is I can't match the pan gesture changing the slider in the same was as the default.  Since you have to implement the pan and adjust the positions yourself, it's difficult to match the real behavior.</p>
  
  <p>None of these methods actually works for me.  Has anyone been able to solve this?  The only solution I can think of is to prevent scrolling all together, add left/right buttons, and programmatically transition pages accordingly. </p>