relationship

// Don't worry about the @NSManaged thing.
// it's just a cue to the compiler that the property
// will be managed by Core Date
class Note: NSManagedObject {
	@NSManaged var notebook : Notebook
}

class Notebook: NSManagedObject {
	@NSManaged var note : ????
}

import CoreData
struct CoreDataStack {
	// MARK: - Properties
	private let model : NSManagedObjectModel
	private let coordinator : MSPersistentStoreCoordinator
	private let modelURL : NSURL
	private let dbURL : NSURL
	let context : NSManagedObjectContext

	// MARK: - Initializers
	init?(modelName: String){

		guard let modelURL = NSBundle.mainBundle().URLForResource(modelName,
			withExtension: "momd") else {
				print("Unable to find \(modelName)in the main bundle")
				return nil}
		self.modelURL = model URL

		// Try to create the model from the URL
		guard let model = NSManagedObjectModel(contentsOfURL: modelURL) else{
			print("unable to create a model from \(modelURL)")
		}
		self.model = model

		coordinator = NSPersistentStoreCoordinator(managedObjectModel: model)

		context = NSManagedObjectContext(concurrencyType: .
			MainQueueConcurrencyType)
		context.persistentStoreCoordinator = coordinator

		// Add a SQLite store located in the documents folder
		let fm = NSFileManager.defaultManager()

		guard let docUrl = fm.URLsForDirectory(.DocumentDirectory, inDomains: UserDomainMask).first else {
			print("manage to people the document folder")
			return nil
		}
	}
}