ios - 核心数据 - 无法加载数据，找不到实体

Question

我已经通过 Core Data 创建了一个简单的 1 实体数据模型。我在“AppDelegate”的“didFinishLaunchingWithOptions”中添加了一个实体。然后，我试图将模型的数据加载到一个数组，然后是一个 TableView 。 我知道有类似的帖子，但我仍然无法找出我的代码有什么问题。

• 我尝试过和检查过的事情列表:
• 实体已正确添加到模型中
• 我已经检查过实体名称，它们是正确的。
• 我已经尝试删除该应用程序并彻底重建它，但仍然没有任何效果。

所以我的代码肯定有更严重的问题。感谢您的帮助。

这是我的错误:

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'FavoritesInfo'

AppDelegate.h

#import <UIKit/UIKit.h>
#import "favTable.h"

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;
@property (strong, nonatomic) favTable *viewController;
@property (strong, nonatomic) UINavigationController *navController;


@property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel;
@property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
@property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;


- (NSURL *)applicationDocumentsDirectory; // reference files for core data


@end

AppDelegate.m

  #import "AppDelegate.h"

    @implementation AppDelegate

    @synthesize window = _window;
    @synthesize viewController = _viewController;
    @synthesize navController = _navController;

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



    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {

        NSManagedObjectContext *context = [self managedObjectContext];
        NSManagedObject *favoritesInfo = [NSEntityDescription
                                           insertNewObjectForEntityForName:@"FavoritesInfo"
                                           inManagedObjectContext:context];
        [favoritesInfo setValue:@"Product 1" forKey:@"name"];
        [favoritesInfo setValue:[NSNumber numberWithInt:15] forKey:@"score"];


        NSError *error;
        if (![context save:&error]) {
            NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
        }


        return YES;
    }

然后在tableviewcontroller的类中favtable.h

   #import <UIKit/UIKit.h>


    @interface favTable : UITableViewController  <NSFetchedResultsControllerDelegate> 
    {
        NSFetchedResultsController *fetchedResultsController;
        NSManagedObjectContext *managedObjectContext;

        NSArray *favArr;
        int num;

    }

    @property (nonatomic, strong) NSArray *favArr;


    @property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;


    @property (nonatomic, retain) NSFetchedResultsController *fetchedResultsController;

    @end

favtable.m viewdidload

#import "favTable.h"
#import "AppDelegate.h"

@interface favTable ()

@end

@implementation favTable

@synthesize favArr;
@synthesize spVC;
@synthesize managedObjectContext = _managedObjectContext;
@synthesize fetchedResultsController;




- (id)initWithStyle:(UITableViewStyle)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.title = @"Favorites";

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription
                                   entityForName:@"FavoritesInfo" inManagedObjectContext:managedObjectContext];
    [fetchRequest setEntity:entity];



      NSError *error=nil;

    self.favArr=[managedObjectContext executeFetchRequest:fetchRequest error:&error];


    if (error!=nil) {
        NSLog(@" fetchError=%@,details=%@",error,error.userInfo); 
    }
}

Answer 1

您的 managedObjectContext 未在您的 ViewController 中设置。 在您的 AppDelegate didFinishLaunchingWithOptions 中设置它，通常如下所示:

ViewControllerClass *controller = (ViewControllerClass*)self.window.rootViewController;

或使用导航 Controller :

UINavigationController *navigationController = (UINavigationController *)self.window.rootViewController;
ViewControllerClass *controller = (ViewControllerClass *)navigationController.topViewController;

然后:

controller.managedObjectContext = self.managedObjectContext;