Macos 定义NSManagedObjectContext的正确方法？

Macos 定义NSManagedObjectContext的正确方法？,macos,swift,core-data,Macos,Swift,Core Data,在我早期使用CoreData的应用程序中，我使用以下方式定义我的NSManagedObjectContext： class MyViewController: NSViewController { lazy var moc: NSManagedObjectContext? = { let app = NSApplication.sharedApplication().delegate as! AppDelegate if let moc = app.ma

CoreData

NSManagedObjectContext

class MyViewController: NSViewController {

    lazy var moc: NSManagedObjectContext? = {
        let app = NSApplication.sharedApplication().delegate as! AppDelegate
        if let moc = app.managedObjectContext {
            return moc
        } else {
            return nil
        }
    }()

    // ....
}

Eartquakes

NSManagedObjectContext

import Cocoa

class CoreDataStackManager {

    class var sharedManager: CoreDataStackManager {
        struct Singleton {
            static let coreDataStackManager = CoreDataStackManager()
        }
        return Singleton.coreDataStackManager
    }

    // persistenStoreCoordinator etc...

class ApplesViewController: NSViewController {

    private lazy var managedObjectContext: NSManagedObjectContext = {
        let moc = NSManagedObjectContext(concurrencyType: .MainQueueConcurrencyType)

        moc.persistentStoreCoordinator = CoreDataStackManager.sharedManager.persistentStoreCoordinator

        return moc
    }()
}