ios - Swift 核心数据问题 (Xcode 6)

Question

这是我的代码:

var appDel:AppDelegate = (UIApplication.sharedApplication().delegate as AppDelegate!)

var context:NSManagedObjectContext = appDel.managedObjectContext

var newUser = NSEntityDescription.insertNewObjectForEntityForName("User", inManagedObjectContext: context) as NSManagedObject

newUser.setValue("test username", forKey: "firstName")
newUser.setValue("test password", forKey: "lastName")

context.save(nil)

println(newUser)
println("Object Saved.")

我一直在按照本教程的步骤进行操作(除了更改一些变量名称外):

https://www.youtube.com/watch?v=3IDfgATVqHw

我认为我的问题在:

var context:NSManagedObjectContext = appDel.managedObjectContext

“appDel.managedObjectContext”并没有像视频中那样变成绿色(只有在我添加“!”到最后我认为会导致我的应用崩溃的情况下才会变成绿色)

编辑:如果我不放 !，应用程序将无法运行/构建。

编辑 2:应用委托(delegate)代码:

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }

    func applicationWillTerminate(application: UIApplication) {
        // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
        // Saves changes in the application's managed object context before the application terminates.
        self.saveContext()
    }

    // MARK: - Core Data stack

    lazy var applicationDocumentsDirectory: NSURL = {
        // The directory the application uses to store the Core Data store file. This code uses a directory named "Dom.Shift_Grabber" in the application's documents Application Support directory.
        let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
        return urls[urls.count-1] as NSURL
        }()

    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 = NSBundle.mainBundle().URLForResource("Shift_Grabber", withExtension: "momd")!
        return NSManagedObjectModel(contentsOfURL: modelURL)!
        }()

    lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
        // The persistent store coordinator for the application. This implementation creates and return 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
        var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
        let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("Shift_Grabber.sqlite")
        var error: NSError? = nil
        var failureReason = "There was an error creating or loading the application's saved data."
        if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
            coordinator = nil
            // Report any error we got.
            let dict = NSMutableDictionary()
            dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
            dict[NSLocalizedFailureReasonErrorKey] = failureReason
            dict[NSUnderlyingErrorKey] = error
            error = 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 \(error), \(error!.userInfo)")
            abort()
        }

        return coordinator
        }()

    lazy var managedObjectContext: NSManagedObjectContext? = {
        // 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
        if coordinator == nil {
            return nil
        }
        var managedObjectContext = NSManagedObjectContext()
        managedObjectContext.persistentStoreCoordinator = coordinator
        return managedObjectContext
        }()

    // MARK: - Core Data Saving support

    func saveContext () {
        if let moc = self.managedObjectContext {
            var error: NSError? = nil
            if moc.hasChanges && !moc.save(&error) {
                // 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.
                NSLog("Unresolved error \(error), \(error!.userInfo)")
                abort()
            }
        }
    }
}

Answer 1

试试这个代码，我遇到了和你一样的问题，我用这个代码修复了它

    let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
    let managedContext = appDelegate.managedObjectContext!
    let entity =  NSEntityDescription.entityForName("WebsiteTasks",
        inManagedObjectContext:
        managedContext)
    let en = NSManagedObject(entity: entity!,
        insertIntoManagedObjectContext:managedContext)
    en.setValue(websiteName.text, forKey: "websiteName")
    en.setValue(websiteLink.text, forKey: "websiteLink")
    var error: NSError?
    if !managedContext.save(&error) {
        println("Could not save \(error), \(error?.userInfo)")
    }