     static let zoneName = "zoneName"
     static let zoneSubscriptionName = "zoneSubscriptionName"
   }
+  
   // MARK: Entity
-
+  
+  /**
+  *  Entity information for Preference.
+  */
   struct Entity {
     static let name = "Seam_Preference"
     static var entityDescription: NSEntityDescription {

      try! context.save()
    }
    
    func saveZoneSubscriptionName(name: String) {
      let preference = NSEntityDescription.insertNewObjectForEntityForName(Entity.name, inManagedObjectContext: context) as! Preference
      preference.key = Default.zoneSubscriptionName

      try! context.save()
    }
    
    /**
     Helper method to retrieve CloudKit saved custom zone name used by the store.
     
     - throws: CoreData fetch request error.
     
     - returns: An optional that might or might not contain saved custom zone name.
     */
    func zoneName() throws -> String? {
      let fetchRequest = NSFetchRequest(entityName: Entity.name)
      fetchRequest.predicate = NSPredicate.preferenceZoneNamePredicate
      return (try context.executeFetchRequest(fetchRequest).first as? Preference)?.value
    }
    
    /**
     Helper method to retrieve CloudKit saved custom zone subscription name used by the store.
     
     - throws: CoreData fetch request error.
     
     - returns: An optional that might or might not contain saved custom zone subscription name.
     */
    func zoneSubscriptionName() throws -> String? {
      let fetchRequest = NSFetchRequest(entityName: Entity.name)
      fetchRequest.predicate = NSPredicate.preferenceZoneSubscriptionNamePredicate
