     
     // cancel method
     public func cancelAllNotifications() {
-        notificationTimer.invalidate()
+        cancelTimer()
         notifications.removeAll()
     }
     

    }
    
    // MARK: internal notification management
    private func rescheduleNextNotification() {
        
        guard pendingNotification == nil else {

            return
        }
        
        cancelTimer()
        
        notifications.sortInPlace { (n1, n2) -> Bool in
            // n1 is before n2?
