Iphone 我如何控制iCloud何时同步我的核心数据？

我有以下代码，可以将我的核心数据与iCloud同步。不过，我只想在我说的时候同步。例如，仅在wifi上同步。我能做到这一点吗？这是我的密码：

- (NSManagedObjectContext *)managedObjectContext {

    if (managedObjectContext != nil) {
        return managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];

    if (coordinator != nil) {
        NSManagedObjectContext* moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];

        [moc performBlockAndWait:^{
            [moc setPersistentStoreCoordinator: coordinator];
            [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(mergeChangesFrom_iCloud:) name:NSPersistentStoreDidImportUbiquitousContentChangesNotification object:coordinator];
        }];
        managedObjectContext = moc;

        managedObjectContext.mergePolicy = [[NSMergePolicy alloc]
                                            initWithMergeType:NSMergeByPropertyObjectTrumpMergePolicyType];
    }

    return managedObjectContext;
}

- (void)mergeChangesFrom_iCloud:(NSNotification *)notification {

    NSLog(@"Merging in changes from iCloud...");

    NSManagedObjectContext* moc = [self managedObjectContext];

    [moc performBlock:^{

        [moc mergeChangesFromContextDidSaveNotification:notification];

        NSNotification* refreshNotification = [NSNotification notificationWithName:@"SomethingChanged"
                                                                            object:self
                                                                          userInfo:[notification userInfo]];

        [[NSNotificationCenter defaultCenter] postNotification:refreshNotification];
    }];
}
- (NSManagedObjectModel *)managedObjectModel {

    if (managedObjectModel != nil) {
        return managedObjectModel;
    }
    NSString *modelPath = [[NSBundle mainBundle] pathForResource:@"EntryDatabase" ofType:@"momd"];
    NSURL *modelURL = [NSURL fileURLWithPath:modelPath];
    managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];

    return managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

    if((persistentStoreCoordinator != nil)) {
        return persistentStoreCoordinator;
    }

    persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
    NSPersistentStoreCoordinator *psc = persistentStoreCoordinator;

    // Set up iCloud in another thread:

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{

        // ** Note: if you adapt this code for your own use, you MUST change this variable:
        NSString *iCloudEnabledAppID = @"iCloud ID is here, i removed it from stack overflow";

        // ** Note: if you adapt this code for your own use, you should change this variable:
        NSString *dataFileName = @"CoreDataStore.sqlite";

        // ** Note: For basic usage you shouldn't need to change anything else

        NSString *iCloudDataDirectoryName = @"Data.nosync";
        NSString *iCloudLogsDirectoryName = @"Logs";
        NSFileManager *fileManager = [NSFileManager defaultManager];

        NSString *storePath = [[self applicationDocumentsDirectory] stringByAppendingPathComponent:dataFileName];

        NSURL *localStore = [NSURL fileURLWithPath:storePath];

        NSURL *iCloud = [fileManager URLForUbiquityContainerIdentifier:nil];

        if (iCloud) {

            NSLog(@"iCloud is working");

            NSURL *iCloudLogsPath = [NSURL fileURLWithPath:[[iCloud path] stringByAppendingPathComponent:iCloudLogsDirectoryName]];

            NSLog(@"iCloudEnabledAppID = %@",iCloudEnabledAppID);
            NSLog(@"dataFileName = %@", dataFileName);
            NSLog(@"iCloudDataDirectoryName = %@", iCloudDataDirectoryName);
            NSLog(@"iCloudLogsDirectoryName = %@", iCloudLogsDirectoryName);
            NSLog(@"iCloud = %@", iCloud);
            NSLog(@"iCloudLogsPath = %@", iCloudLogsPath);

            if([fileManager fileExistsAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]] == NO) {
                NSError *fileSystemError;
                [fileManager createDirectoryAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]
                       withIntermediateDirectories:YES
                                        attributes:nil
                                             error:&fileSystemError];
                if(fileSystemError != nil) {
                    NSLog(@"Error creating database directory %@", fileSystemError);
                }
            }

            NSString *iCloudData = [[[iCloud path]
                                     stringByAppendingPathComponent:iCloudDataDirectoryName]
                                    stringByAppendingPathComponent:dataFileName];

            NSLog(@"iCloudData = %@", iCloudData);

            NSMutableDictionary *options = [NSMutableDictionary dictionary];
            [options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
            [options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];
            [options setObject:iCloudEnabledAppID            forKey:NSPersistentStoreUbiquitousContentNameKey];
            [options setObject:iCloudLogsPath                forKey:NSPersistentStoreUbiquitousContentURLKey];

            [psc lock];

            [psc addPersistentStoreWithType:NSSQLiteStoreType
                              configuration:nil
                                        URL:[NSURL fileURLWithPath:iCloudData]
                                    options:options
                                      error:nil];

            [psc unlock];
        }
        else {
            NSLog(@"iCloud is NOT working - using a local store");
            NSMutableDictionary *options = [NSMutableDictionary dictionary];
            [options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
            [options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];

            [psc lock];

            [psc addPersistentStoreWithType:NSSQLiteStoreType
                              configuration:nil
                                        URL:localStore
                                    options:options
                                      error:nil];
            [psc unlock];

        }

        dispatch_async(dispatch_get_main_queue(), ^{
            [[NSNotificationCenter defaultCenter] postNotificationName:@"SomethingChanged" object:self userInfo:nil];
        });
    });

    return persistentStoreCoordinator;

 }

---

就我所知，这不可能发生。无论如何，不是以简单有效的方式

问题是，iCloud的运行是不透明的。因此，iOS决定何时进行同步以及同步频率。在上面的文档中，苹果表示“最佳实践”是专门使用沙盒或iCloud，但不要在它们之间复制数据

也就是说，苹果提到了当iCloud不可用时的操作。这似乎符合您建议的情景。基本上，您需要将其设置为正常状态，确保您拥有所需的数据，然后停用iCloud并将数据移动到沙箱中进行处理。如果要同步，只需将数据复制回来

要处理iCloud可用性中的更改，请实现一个在收到NSUbiquityIdentityDidChangeNotification通知时调用的方法。您的方法需要执行以下工作：

调用ubiquityIdentityToken方法并存储其返回值。 将新值与以前的值进行比较，以确定用户是注销了其帐户还是登录到其他帐户。 如果以前使用的帐户现在不可用，请根据需要在本地保存当前状态，清空与iCloud相关的数据缓存，并刷新所有与iCloud相关的用户界面元素。 如果您想允许用户在iCloud不可用的情况下继续创建内容，请将该内容存储在应用程序的沙盒容器中。当帐户再次可用时，将新内容移动到iCloud。通常最好在不通知用户或不需要用户进行任何交互的情况下执行此操作

这似乎符合您的要求。然而，我自己才刚刚达到这一阶段，所以我无法进一步评论。

Ensembles（）是我为同步核心数据而开发的框架。它使您可以控制同步的时间，还将自动迁移和合并现有数据。