Jak utworzyć managedObjectContext przy użyciu Swift 3 w Xcode 8?

Przeniósł cały kod bazowego stosu danych do jednego pliku i dodał iOS 10 i poniżej iOS 10. poniżej moja próba (nie jestem pewien, czy jest w pełni do znaku)

import Foundation
import CoreData

class CoreDataManager {
    // MARK: - Core Data stack
    static let sharedInstance = CoreDataManager()

    private lazy var applicationDocumentsDirectory: URL = {
        // The directory the application uses to store the Core Data store file. This code uses a directory named in the application's documents Application Support directory.
        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return urls[urls.count-1]
    }()

    private lazy var managedObjectModel: NSManagedObjectModel = {
        // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
        let modelURL = Bundle.main.url(forResource: "CoreDataSwift", withExtension: "momd")!
        return NSManagedObjectModel(contentsOf: modelURL)!
    }()

    private lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator = {
        // The persistent store coordinator for the application. This implementation creates and returns a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
        // Create the coordinator and store
        let coordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
        let url = self.applicationDocumentsDirectory.appendingPathComponent("CoreDataSwift.sqlite")
        var failureReason = "There was an error creating or loading the application's saved data."
        do {
            // Configure automatic migration.
            let options = [ NSMigratePersistentStoresAutomaticallyOption : true, NSInferMappingModelAutomaticallyOption : true ]
            try coordinator.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: url, options: options)
        } catch {
            // Report any error we got.
            var dict = [String: AnyObject]()
            dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data" as AnyObject?
            dict[NSLocalizedFailureReasonErrorKey] = failureReason as AnyObject?

            dict[NSUnderlyingErrorKey] = error as NSError
            let wrappedError = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
            // Replace this with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog("Unresolved error \(wrappedError), \(wrappedError.userInfo)")
            abort()
        }

        return coordinator
    }()

    lazy var managedObjectContext: NSManagedObjectContext = {

        var managedObjectContext: NSManagedObjectContext?
        if #available(iOS 10.0, *){

            managedObjectContext = self.persistentContainer.viewContext
        }
        else{
        // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
        let coordinator = self.persistentStoreCoordinator
        managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        managedObjectContext?.persistentStoreCoordinator = coordinator

        }
        return managedObjectContext!
    }()
    // iOS-10
    @available(iOS 10.0, *)
    lazy var persistentContainer: NSPersistentContainer = {
        /*
         The persistent container for the application. This implementation
         creates and returns a container, having loaded the store for the
         application to it. This property is optional since there are legitimate
         error conditions that could cause the creation of the store to fail.
         */
        let container = NSPersistentContainer(name: "CoreDataSwift")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                // Replace this implementation with code to handle the error appropriately.
                // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

                /*
                 Typical reasons for an error here include:
                 * The parent directory does not exist, cannot be created, or disallows writing.
                 * The persistent store is not accessible, due to permissions or data protection when the device is locked.
                 * The device is out of space.
                 * The store could not be migrated to the current model version.
                 Check the error message to determine what the actual problem was.
                 */
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        print("\(self.applicationDocumentsDirectory)")
        return container
    }()
    // MARK: - Core Data Saving support

    func saveContext () {
        if managedObjectContext.hasChanges {
            do {
                try managedObjectContext.save()
            } catch {
                // Replace this implementation with code to handle the error appropriately.
                // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
                let nserror = error as NSError
                NSLog("Unresolved error \(nserror), \(nserror.userInfo)")
                abort()
            }
        }
    }
}

Rozwiązanie przez James Amo daje ci większość drogi tam dla iOS 10.0, ale nie odnosi się do iOS 9.0 i poniżej, który nie może uzyskać dostępu do tej metody i musi ręcznie zbudować NSManagedObjectModel. Oto rozwiązanie, które zadziałało dla mnie:

    var context: NSManagedObjectContext?

    if #available(iOS 10.0, *) {
        context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    } else {
        // iOS 9.0 and below - however you were previously handling it
        guard let modelURL = Bundle.main.url(forResource: "Model", withExtension:"momd") else {
            fatalError("Error loading model from bundle")
        }
        guard let mom = NSManagedObjectModel(contentsOf: modelURL) else {
            fatalError("Error initializing mom from: \(modelURL)")
        }
        let psc = NSPersistentStoreCoordinator(managedObjectModel: mom)
        context = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
        let urls = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        let docURL = urls[urls.endIndex-1]
        let storeURL = docURL.appendingPathComponent("Model.sqlite")
        do {
            try psc.addPersistentStore(ofType: NSSQLiteStoreType, configurationName: nil, at: storeURL, options: nil)
        } catch {
            fatalError("Error migrating store: \(error)")
        }

    }

Jasne jest, że zmiana na 10.0 znacznie upraszcza Coredatę, ale szkoda, że tak bolesne jest dla obecnych programistów wykonanie skoku...

Aby zaimplementować powyższe, po prostu wrzuć persistentContainer do swojego AppDelegate.swift, zdefiniowany w odpowiedziJamesa Amo .

NSPersistentContainer posiada właściwość viewContext będącą typem NSManagedObjectContext.

Na marginesie, jeśli utworzysz aplikację Master-Detail w Xcode 8, przykładowy kod Apple ' a umieszcza Właściwość managedObjectContext w kontrolerze MasterViewController.plik swift i ustawia go za pomocą właściwości viewContext w AppDelegate.

Najpierw pobierz obiekt AppDelegate:-

let appDelegateObject = UIApplication.shared.delegate as! AppDelegate

I teraz możemy otrzymać zarządzany obiekt jako:

let managedObject = appDelegateObject.persistentContainer.viewContext