Core data 设置持久存储和父上下文

当

NSManagedObjectContext

同时设置了持久存储和父上下文并调用save时会发生什么情况？它会将数据一个接一个地推送到持久存储和父上下文吗？还是会同时进行？或者核心数据只是抛出一个抱怨异常

API不会直接阻止一个人为给定上下文设置两个“父项”。

这将发生：

***由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“上下文已经有一个协调器；无法替换。“

这是因为当您设置

parentContext

时，

persistentstorecordinator

会自动设置为父上下文的

persistentstorecordinator

这将发生：

***由于未捕获的异常“NSInternalInconsistencyException”而终止应用程序，原因：“上下文已经有一个协调器；无法替换。“

---

这是因为当您设置

parentContext

时，

persistentstorecordinator

会自动设置为父上下文的

persistentstorecordinator

如果为父上下文分配协调器，则不需要为托管上下文设置协调器

NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    [self setManagedObjectContext:moc];

    [self setPrivateContext:[[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]];

    /// when you set parentContext, the persistentStoreCoordinator is automatically set to the persistentStoreCoordinator of the parent contex
    [self.privateContext setPersistentStoreCoordinator:coordinator];
    [self.managedObjectContext setParentContext:self.privateContext];

以下是在框架示例中使用的完整代码-

    NSURL *modelURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TVModelSDK" withExtension:@"momd"];
    NSManagedObjectModel *mom = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    NSAssert(mom, @"Failed to initialize mom from URL: %@", modelURL);

    NSPersistentStoreCoordinator *coordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:mom];

    NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    /// DONOT set coordinator for managed Context ! 
    // [moc setPersistentStoreCoordinator:coordinator];
    [self setManagedObjectContext:moc];

    [self setPrivateContext:[[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]];
    /// when you set parentContext, the persistentStoreCoordinator is automatically set to the persistentStoreCoordinator of the parent contex
    [self.privateContext setPersistentStoreCoordinator:coordinator];
    [self.managedObjectContext setParentContext:self.privateContext];

---

如果为父上下文分配协调器，则不需要为托管上下文设置协调器

NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    [self setManagedObjectContext:moc];

    [self setPrivateContext:[[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]];

    /// when you set parentContext, the persistentStoreCoordinator is automatically set to the persistentStoreCoordinator of the parent contex
    [self.privateContext setPersistentStoreCoordinator:coordinator];
    [self.managedObjectContext setParentContext:self.privateContext];

以下是在框架示例中使用的完整代码-

    NSURL *modelURL = [[NSBundle bundleForClass:[self class]] URLForResource:@"TVModelSDK" withExtension:@"momd"];
    NSManagedObjectModel *mom = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    NSAssert(mom, @"Failed to initialize mom from URL: %@", modelURL);

    NSPersistentStoreCoordinator *coordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:mom];

    NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
    /// DONOT set coordinator for managed Context ! 
    // [moc setPersistentStoreCoordinator:coordinator];
    [self setManagedObjectContext:moc];

    [self setPrivateContext:[[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType]];
    /// when you set parentContext, the persistentStoreCoordinator is automatically set to the persistentStoreCoordinator of the parent contex
    [self.privateContext setPersistentStoreCoordinator:coordinator];
    [self.managedObjectContext setParentContext:self.privateContext];

谢谢“persistentStoreCoordinator自动设置为父上下文的persistentStoreCoordinator”您能详细说明一下吗？如果我有3个上下文A->B->C->persistent store，并且我刚刚插入了一些数据并想要保存它，我应该在A上调用save，在块内调用save-on-B，然后在另一个嵌套块内调用save-on-C吗？谢谢！“persistentStoreCoordinator自动设置为父上下文的persistentStoreCoordinator”您能详细说明一下吗？如果我有3个上下文A->B->C->persistent store，并且我刚刚插入了一些数据并想要保存它，我应该在A上调用save，在块内调用save-on-B，然后在另一个嵌套块内调用save-on-C吗？