         return true
     }
     
-    override func continueTrackingWithTouch(touch: UITouch!, withEvent event: UIEvent!) -> Bool {
+    override func continueTrackingWithTouch(touch: UITouch, withEvent event: UIEvent) -> Bool {
         super.continueTrackingWithTouch(touch, withEvent: event)
         
         // Get touch location

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

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