title: Knowing when a view is going to be destroyed in UIView lifecycle
body: <p>I have a UIView which is part of a UIPageViewController.
  I pass a strong object to this view, and am having problem with releasing.</p>
  
  <p>In the past I think I used viewDidUnload to release any strong objects, and then Dealloc is called. Now deal is never called because of the strong objects.</p>
  
  <p>What is the best way to know icm with a UIPageViewController that the object is not needed anymore. I.e. if it is the view beside the page the user is looking at, it might come back into view. So using viewWillDisappeart will not work I expect.</p>
  
  <pre><code>@interface DOTourFloorPlanViewController : UIViewController &lt;UIScrollViewDelegate, DOAsyncImageViewDelegate&gt; {
      IBOutlet DOAsyncImageView* _imageView;
      IBOutlet UIScrollView* _scrollView;
  
      NSMutableArray* _beaconLabels;
  
      UIView* _circle;
      UIView* _centerDot;
  
      DOTour* _tour;
      CGRect _zoomRect;
  
      int _circleCenterX;
      int _circleCenterY;
  
      bool _didZoomToLocation;
  }
  
  @property (strong, nonatomic) DOTour* tour;
  </code></pre>