             println("ref \(reference) & val \(value)")
         }
     }
+    
+    func showAdvert() {
+        // show an advert if they haven't left a tip
+        let leftTip = NSUserDefaults.standardUserDefaults().boolForKey("kDidLeaveDonation")
+        if !leftTip {
+            println("Display advert")
+            BatchAds.displayAdForPlacement(BatchPlacementDefault)
+        }
+    }
 }
        
        // If we're returning we need to check if goal progress has elapsed
        IGIGoal.cleanElapsedGoals()
    }
    
    func application(application: UIApplication, didReceiveLocalNotification notification: UILocalNotification) {

        
        // If we crashed, or the user left the app, let's start the entry over
        IGIGoal.cleanInvalidGoals()
                
        return true
    }
    
