         self.on = false
     }
     
-    override func beginTrackingWithTouch(touch: UITouch, withEvent event: UIEvent) -> Bool {
+    override public func beginTrackingWithTouch(touch: UITouch, withEvent event: UIEvent) -> Bool {
         super.beginTrackingWithTouch(touch, withEvent: event)
         
         startTrackingValue = self.on

        }
    }
    
    override func cancelTrackingWithEvent(event: UIEvent?) {
        super.cancelTrackingWithEvent(event)
        
        // just animate back to the original value

    *   The image is centered in the area not covered by the knob.
    *   Make sure to size your images appropriately.
    */
    @IBInspectable public var onImage: UIImage! {
        willSet {
            onImageView.image = newValue
        }
    }
    
    /*
