コアデータエラー：nilは合法的なNSManagedObjectContextパラメータではありません

Question

私はiOSアプリケーションを作成することに全く新しいです。私はすぐにフォームアプリケーションを作成して、それを記入したい人からの情報を保存することができます。名前、メールなどのテキストフィールドの基本的な束。

フォームは、これらのデータを以下のコードで保存しています。

//Save action 
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Person" inManagedObjectContext: context]; 
NSManagedObject *newPerson = [[NSManagedObject alloc]initWithEntity:entityDesc insertIntoManagedObjectContext:context]; 

//Fill in values 
[newPerson setValue:self.btnPrefix.titleLabel.text forKey: @"prefix"]; 
[newPerson setValue:self.txtFirstName.text forKey: @"firstname"]; 
[newPerson setValue:self.txtLastName.text forKey: @"lastname"]; 
[newPerson setValue:self.txtLive.text forKey: @"country"]; 
[newPerson setValue:self.txtMail.text forKey: @"email"]; 
[newPerson setValue:self.txtPhone.text forKey: @"phonenumber"]; 
[newPerson setValue:self.txtLinked.text forKey: @"linkedIn"]; 
[newPerson setValue:self.txtAbout.text forKey: @"about"]; 

NSError *error; 
[context save:&error]; 

シミュレータ上で実行しても問題はありません。それが最初の行にtriggerdますデバッグ後

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Person''

：しかし、かつて私はこのエラーを取得するiPad上で実行に実行したとき

NSEntityDescription *entityDesc = [NSEntityDescription entityForName:@"Person" inManagedObjectContext: context]; 

もう少し研究した後は、私のAppdelegateは皆無persistentContainerが含まれています仮想デバイスで実行されるといっぱいになります。だから私は問題がそこにあると思うが、私はそれを解決する方法を見つけることができない。

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    AppDelegate *appdelegate = (AppDelegate*)[[UIApplication sharedApplication]delegate]; 
    context = appdelegate.persistentContainer.viewContext; 
} 

誰でもお手伝いできますか？

Answer 1

このエラーが発生した場合。おそらく仮想デバイスでは動作しますが、物理デバイスでは動作しないのは、iOS 9と10の間でコアデータにアクセスするための違いが原因です。

XD8では、AppDelegateは自動的にiOS 10のデータを生成します。あなたは、デリゲートのファイルに次のコードを追加する必要がありますiOSの9に貼り付け：

- (void)saveContext { 
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext; 
    if(managedObjectContext != nil){ 
     NSError *error = nil; 
     if([managedObjectContext hasChanges] && ![managedObjectContext save:&error]){ 
      NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
      abort(); 
     } 
    } 

    //For iOS 10 and above 
    /* 
    NSManagedObjectContext *context = self.persistentContainer.viewContext; 
    NSError *error = nil; 
    if ([context hasChanges] && ![context 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 2

プライベート怠惰のvar applicationDocumentsDirectory：URL = { //

@synthesize managedObjectContext = _managedObjectContext; 
@synthesize managedObjectModel = _managedObjectModel; 
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator; 

- (NSURL *) applicationDocumentsDirectory{ 
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; 
} 

- (NSManagedObjectModel *)managedObjectModel { 
    if(_managedObjectModel != nil){ 
     return _managedObjectModel; 
    } 
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"StylelabsForms" withExtension:@"momd"]; 
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL]; 
    return _managedObjectModel; 
} 

- (NSPersistentStoreCoordinator *) persistentStoreCoordinator{ 
    if(_persistentStoreCoordinator != nil){ 
     return _persistentStoreCoordinator; 
    } 

    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; 
    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"StylelabsForms.sqlite"]; 
    NSError *error = nil; 
    NSString *failureReason = @"Error loading saved data"; 
    if(![_persistentStoreCoordinator addPersistentStoreWithType: NSSQLiteStoreType configuration:nil URL: storeURL options:nil error:&error]){ 
     NSMutableDictionary *dict = [NSMutableDictionary dictionary]; 
     dict[NSLocalizedDescriptionKey] = @"Failed init application's saved data"; 
     dict[NSLocalizedFailureReasonErrorKey] = failureReason; 
     dict[NSUnderlyingErrorKey] = error; 
     error = [NSError errorWithDomain:@"YOUR_ERROR_DOMAIN" code:9999 userInfo:dict]; 
     NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
     abort(); 
    } 

    return _persistentStoreCoordinator; 
} 

- (NSManagedObjectContext *) managedObjectContext { 
    if (_managedObjectContext != nil){ 
     return _managedObjectContext; 
    } 

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator]; 
    if(!coordinator) { 
     return nil; 
    } 
    _managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType]; 
    [_managedObjectContext setPersistentStoreCoordinator:coordinator]; 

    return _managedObjectContext; 
} 

も続くとして保存を適応させますディレクトリthアプリケーションは、コアデータストアファイルを格納するために使用します。このコードでは、アプリケーションのドキュメントApplication Supportディレクトリにあるディレクトリを使用します。 （：で.documentDirectory、：.userDomainMask用） リターンのURL [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: "CoreData", 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("CoreData.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: "CoreData") 
    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)") 
     } 
    }) 
    print("\(self.applicationDocumentsDirectory)") 
    return container 
}()