使用Swift将CoreData实现到现有项目中
我目前正在使用Xcode 6 beta 7，并决定在创build我的项目之后我需要CoreData。 我已经看了一些已经问这个问题的客观C与一些在这个问题上观看video，但我似乎得到同样的错误。 至于我使用CoreData框架本身，我敢肯定，这是正确的，因为我创build了另一个空项目（核心数据框选中），并遵循相同的实施，它的工作像一个魅力，但可能有什么问题，我是也在那里做。 所以下面是我在Swift项目中实现CoreData的步骤。
第一步：我通过“Build Phases”下的“Link Binary with Libraries”标签添加了CoreData框架。
第2步：然后我去我的任何.swift文件需要实现CoreData（appDelegate.swift和另一个文件截至目前为止），并添加行：
import CoreData 到顶部。
第3步：我创build了一个名为“cData”的实体的数据列表，然后为它创build了一个名为“data.swift”的类。 这里是data.swift：
import UIKit import CoreData @objc( data ) class data: NSManagedObject { @NSManaged var something : String }
第四步：我写了代码来实际上将数据保存在另一个文件中：
@IBAction func useCoreData(sender: AnyObject) { let AD : AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate let ct : NSManagedObjectContext = AD.managedObjectContext! let ent = NSEntityDescription.entityForName( "CData", inManagedObjectContext: ct ) var dat = data( entity: ent!, insertIntoManagedObjectContext: ct ) dat.something = someTextField.text ct.save( nil ) println(dat) }
第5步：这里是我相信我搞砸了，但我可能是错的。 我在一个单独的Mac上创build了一个新项目（所以我可以把它命名为相同的东西），并检查了CoreData框。 然后我把这个项目中的整个appDelegate.swift复制到当前的项目中。 这是我的appDelegate.swift：
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 applicationWillResignActive(application: UIApplication) { // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state. // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game. } func applicationDidEnterBackground(application: UIApplication) { // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later. // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits. } func applicationWillEnterForeground(application: UIApplication) { // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background. } func applicationDidBecomeActive(application: UIApplication) { // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface. } 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 "y.Simple_Grade" 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("my_app", 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("my_app.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.errorWithDomain("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() } } } }
一旦调用IBAction方法“useCoreData”，我得到一个崩溃，exception状态“致命错误：意外地发现零，而解包一个可选的值（lldb）”，并指出有问题的行是在appDelegate.swift：
let modelURL = NSBundle.mainBundle().URLForResource("my_app", withExtension: "momd")!
再一次，当我在另一个项目中尝试使用同样的CoreData实现时，从一开始就检查了CoreData框，它就像一个魅力。 我看到类似的问题（用户得到同样的错误），但似乎他的问题也没有解决。
你得到一个nil值，因为它正在寻找的文件不存在于你的主包中。
您需要将您创build的其他项目的数据模型文件复制到主项目中。 该文件将被称为像My_App.xcdatamodeld ，应该位于您的Xcode项目文件所在的文件夹中。
注意： URLForResource行正在寻找My_App.momd ; 该文件是由编译您的项目时从My_App.xcdatamodeld的Xcode创build的。