         self.addGestureRecognizer(leftSwipeGestureRecognier)
         self.addGestureRecognizer(rightSwipeGestureRecognier)
         
+        // add UIPinchGestureRecognizers
+        let pinchGestureRecognizer: UIPinchGestureRecognizer = UIPinchGestureRecognizer()
+        self.addGestureRecognizer(pinchGestureRecognizer)
     }
     
     // Only override drawRect: if you perform custom drawing.


            }
        }
        
        return true
    }

    private var numberOfPages: size_t = 0
    private var currentPage: size_t = 1

    private var scale: CGFloat = 0.0
    
    required init?(coder aDecoder: NSCoder)
    {
        super.init(coder: aDecoder)
