 			static var onceToken: dispatch_once_t = 0
 			static var managedObjectContext: NSManagedObjectContext!
 		}
-		dispatch_once(&GKGraphManagedObjectContext.onceToken) {[weak self] in
+		dispatch_once(&GKGraphManagedObjectContext.onceToken) { [weak self] in
 			GKGraphManagedObjectContext.managedObjectContext = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)
 			GKGraphManagedObjectContext.managedObjectContext.persistentStoreCoordinator = self!.persistentStoreCoordinator
 		}

			static var onceToken: dispatch_once_t = 0
			static var persistentStoreCoordinator: NSPersistentStoreCoordinator!
		}
		dispatch_once(&GKGraphPersistentStoreCoordinator.onceToken) {[weak self] in
			let storeURL = self!.applicationDocumentsDirectory.URLByAppendingPathComponent(GKGraphUtility.storeName)
			var error: NSError?
			GKGraphPersistentStoreCoordinator.persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: self!.managedObjectModel)

	* @param        completion: (success: Bool, error: NSError?) -> ())
	*/
	public func save(completion: (success: Bool, error: NSError?) -> ()) {
		managedObjectContext.performBlockAndWait { [weak self] in
			if !self!.managedObjectContext.hasChanges {
				completion(success: true, error: nil)
				return
