Question

我有3个核心数据管理对象文件：

CoreDataModel.xcdatamodeld
CoreDataModel_Small.xcdatamodeld
CoreDataModel_MyLocations.xcdatamodeld

在这样配置它们：

AppDelegate.h：

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

/////// CoreDataModel_Small ///////
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext_small;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel_small;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator_small;

/////// CoreDataModel_MyLocations ///////
@property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext_MyLocations;
@property (readonly, strong, nonatomic) NSManagedObjectModel *managedObjectModel_MyLocations;
@property (readonly, strong, nonatomic) NSPersistentStoreCoordinator *persistentStoreCoordinator_MyLocations;

AppDelegate.m：

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

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

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

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

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataModel.sqlite"];
    NSError *error = nil;
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

    NSDictionary *options = @{NSMigratePersistentStoresAutomaticallyOption : @YES,
                              NSInferMappingModelAutomaticallyOption : @YES,
                              NSSQLiteManualVacuumOption : @YES};

    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _persistentStoreCoordinator;
}

//////////// CoreDataModel_Small ////////////

- (NSManagedObjectContext *)managedObjectContext_small
{
    if (_managedObjectContext_small != nil) {
        return _managedObjectContext_small;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator_small];
    if (coordinator != nil) {
        _managedObjectContext_small = [[NSManagedObjectContext alloc] init];
        [_managedObjectContext_small setPersistentStoreCoordinator:coordinator];
    }
    return _managedObjectContext_small;
}

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

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator_small
{
    if (_persistentStoreCoordinator_small != nil) {
        return _persistentStoreCoordinator_small;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataSmall.sqlite"];
    NSError *error = nil;
    _persistentStoreCoordinator_small = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel_small]];

    NSDictionary *options = @{NSMigratePersistentStoresAutomaticallyOption : @YES,
                              NSInferMappingModelAutomaticallyOption : @YES,
                              NSSQLiteManualVacuumOption : @YES};

    if (![_persistentStoreCoordinator_small addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        // abort();
    }

    return _persistentStoreCoordinator;
}

//////////// CoreDataModel_MyLocations ////////////

- (NSManagedObjectContext *)managedObjectContext_MyLocations
{
    if (_managedObjectContext_MyLocations != nil) {
        return _managedObjectContext_MyLocations;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator_MyLocations];
    if (coordinator != nil) {
        _managedObjectContext_MyLocations = [[NSManagedObjectContext alloc] init];
        [_managedObjectContext_MyLocations setPersistentStoreCoordinator:coordinator];
    }
    return _managedObjectContext_MyLocations;
}

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

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator_MyLocations
{
    if (_persistentStoreCoordinator_MyLocations != nil) {
        return _persistentStoreCoordinator_MyLocations;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataMyLocations.sqlite"];
    NSError *error = nil;
    _persistentStoreCoordinator_MyLocations = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel_MyLocations]];

    NSDictionary *options = @{NSMigratePersistentStoresAutomaticallyOption : @YES,
                              NSInferMappingModelAutomaticallyOption : @YES,
                              NSSQLiteManualVacuumOption : @YES};

    if (![_persistentStoreCoordinator_MyLocations addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        // abort();
    }

    return _persistentStoreCoordinator;
}

并调用正确的上下文：

FOUNDATION_EXPORT NSManagedObjectContext *generateManagedObjectContext(CoreDataType type)
{
    NSManagedObjectContext *context = [[NSManagedObjectContext alloc] init];

    if (type == CoreDataTypeBig) {
        context.persistentStoreCoordinator = appDelegate.persistentStoreCoordinator;
    }
    else if (type == CoreDataTypeSmall) {
        context.persistentStoreCoordinator = appDelegate.persistentStoreCoordinator_small;
    }
    else if (type == CoreDataTypeMyLocations) {
        context.persistentStoreCoordinator = appDelegate.persistentStoreCoordinator_MyLocations;
    }

    if ([NSThread isMainThread])    { [context setMergePolicy:NSMergeByPropertyObjectTrumpMergePolicy]; }
    else                            { [context setMergePolicy:NSMergeByPropertyStoreTrumpMergePolicy]; }

    return context;
}

但是我的一个方法中有一个错误，当从特定实体中删除所有对象时，我之前没有遇到过这个问题，因为我在一个.xcdatamodeld文件中管理了所有对象，我决定将其分开他们：

获取请求必须具有实体

我认为其中一个问题是当我保存上下文（在AppDelegate.m文件中）时，该函数保持平常，我确信我需要以某种方式使其保存到正确的{{ 1}}。

编辑1：

产生错误的代码：

NSManagedObjectContext

Answer 1

该错误告诉您的是，当您进行提取时，entity为零。很难确定为什么会发生这种情况。你似乎是：

查找persistentStoreCoordinator_MyLocations（使用CoreDataModel_MyLocations.momd处的数据模型）
在使用该持久性商店协调员的托管对象上下文中查找名称存储在kCORE_DATA_LOCATION_ENTITY中的实体。
获取该实体

这意味着kCORE_DATA_LOCATION_ENTITY中的任何内容都与CoreDataModel_MyLocations.momd中的实体名称不匹配。这可能就像拼写错误一样简单。要检查的第一件事是实体名称完全匹配。

如果名称匹配，则下一步是对Core Data堆栈进行更深入的验证。应用包中是否存在CoreDataModel_MyLocations.momd？ persistentStoreCoordinator_MyLocations是否已正确初始化？验证堆栈中没有任何内容nil或以其他方式丢失。

另外，有些人报告说这个问题是旧应用程序安装的副作用，导致一些框架混乱。确保从测试设备和模拟器中删除任何以前的应用程序副本，并进行干净的构建。

多个.xcdatamodeld核心数据文件，如何保存到正确的一个？

1 个答案: