         if self.calendarChooser == nil {
             presentCalendarChooser()
         }
+    }
+    
+    override func viewWillDisappear(animated: Bool) {
+        super.viewWillDisappear(animated)
+
+        NSNotificationCenter.defaultCenter().removeObserver(self)
     }
 
     // MARK: Private

        navigationController?.navigationBar.setBackgroundImage(UIImage(named: "background"), forBarMetrics: UIBarMetrics.Default)
        navigationController?.navigationBar.titleTextAttributes = [NSFontAttributeName: UIFont.systemFontOfSize(24)]
        updateNavigationBarTitle()
    }

    override func viewDidAppear(animated: Bool) {


        self.dismissViewControllerAnimated(true, completion: nil)
    }
    
    // MARK: UIApplicationNotification
    
    func applicationSignificantTimeChange(notification: NSNotification) {
        updateNavigationBarTitle()
    }

    // MARK: Key Value Observing
    
