Question

我有一个名为TestProject的xcode4项目即将尝试添加CoreData。我添加了一个带有几个实体的数据模型（名为TestDataModel），并为实体创建了NSManagedObject类。

我的问题是我无法加载Persistent Store

if(self.managedObjectContext == nil){
        NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
        NSString* basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
        NSURL* storeUrl = [NSURL fileURLWithPath:[basePath stringByAppendingPathComponent: @"TestProject.sqlite"]];
        NSError* errors;

        NSPersistentStoreCoordinator* persistentStoreCoordinator = 
                           [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[NSManagedObjectModel 
                                                                     mergedModelFromBundles:nil ]];

        if(![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType 
                                                     configuration:nil 
                                                               URL:storeUrl 
                                                           options:nil 
                                                             error:&errors])
        {
            NSLog(@"Error loading persistent store: %@", [errors localizedDescription]);
        }

        self.managedObjectContext = [[NSManagedObjectContext alloc] init];
        [self.managedObjectContext setPersistentStoreCoordinator:persistentStoreCoordinator];

    }

我继续收到错误：

Error loading persistant store: The operation couldn’t be completed. (Cocoa error 258.)

请注意我也在模拟器中运行它。

提前致谢。

Answer 1

您使用的是错误的目录。

NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentationDirectory, NSUserDomainMask, YES);
                                                     ^^^^^^^^^^^^^^^^^^^^^^^^

将此更改为

NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
                                                     ^^^^^^^^^^^^^^^^^^^

NSDocumentDirectory由iOS创建，但NSDocumentationDirectory目录不是。

Answer 2

想出来。没意识到我需要创建数据库

代码下方

if(self.managedObjectContext == nil){

        NSString *storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent:@"TestProject.sqlite"];

        NSFileManager *fileManager = [NSFileManager defaultManager];
        if (![fileManager fileExistsAtPath:storePath]) {
            NSString *defaultStorePath = [[NSBundle mainBundle] pathForResource:@"TestProject" ofType:@"sqlite"];
            if (defaultStorePath) {
                [fileManager copyItemAtPath:defaultStorePath toPath:storePath error:NULL];
            }
        }

        NSURL *storeUrl = [NSURL fileURLWithPath:storePath];


        NSError* errors;
        NSPersistentStoreCoordinator* persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[NSManagedObjectModel mergedModelFromBundles:nil]];

        if(![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&errors])
        {
            NSLog(@"Error loading persistent store: %@", [errors localizedDescription]);
        }

        self.managedObjectContext = [[NSManagedObjectContext alloc] init];
        [self.managedObjectContext setPersistentStoreCoordinator:persistentStoreCoordinator];

    }

你还需要这个

- (NSString *)applicationDocumentsDirectory {
    return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
}

IOS核心数据 - 无法加载NSPersistentStoreCoordinator

2 个答案: