iOS:将现有Core Data数据库迁移到iCloud

Question

我在现有应用程序中使用Core Data.现在我想集成iCloud,以便用户可以在他们的iOS设备之间同步他们的内容.为此,我为我的NSPersistentStoreCoordinator编写了以下代码(当然占位符在我的代码中填写):

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {

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

NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"<DB_Name>.sqlite"];

persistentStoreCoordinator_ = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];

NSPersistentStoreCoordinator* psc = persistentStoreCoordinator_;

if (IOS_VERSION_GREATER_THAN_OR_EQUAL_TO(@"5.0")) {
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        NSFileManager *fileManager = [NSFileManager defaultManager];

        // Migrate datamodel
        NSDictionary *options = nil;

        // this needs to match the entitlements and provisioning profile
        NSURL *cloudURL = [fileManager URLForUbiquityContainerIdentifier:@"<App_Identifier>"];
        NSString* coreDataCloudContent = [[cloudURL path] stringByAppendingPathComponent:@"data"];
        if ([coreDataCloudContent length] != 0) {
            // iCloud is available
            cloudURL = [NSURL fileURLWithPath:coreDataCloudContent];

            options = [NSDictionary dictionaryWithObjectsAndKeys:
                       [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                       [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
                       @"<App_Name>.store", NSPersistentStoreUbiquitousContentNameKey,
                       cloudURL, NSPersistentStoreUbiquitousContentURLKey,
                       nil];
        } else {
            // iCloud is not available
            options = [NSDictionary dictionaryWithObjectsAndKeys:
                       [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                       [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
                       nil];
        }

        NSError *error = nil;
        [psc lock];
        if (![psc addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:options error:&error])
        {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        }
        [psc unlock];

        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"asynchronously added persistent store!");
            [[NSNotificationCenter defaultCenter] postNotificationName:@"RefetchAllDatabaseData" object:self userInfo:nil];
        });

    });

} else {
    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
                             [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                             [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption,
                             nil];

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

return persistentStoreCoordinator_;
}

使用该代码,所有新添加的数据记录将在所有iOS设备之间自动同步,因此它的工作方式完全正确!

但我想要的是,所有现有的数据记录都在所有设备之间同步; 那还行不通.现有记录仍然可以在应用程序中使用并且可以使用,但它们不同步.

我还需要做些什么来使所有现有数据记录与iCloud同步？我用这种方法做了一些实验

migratePersistentStore:toURL:options:withType:error:

但没有任何成功.

我非常感谢任何帮助!

Answer 1

查找 WWDC 2012 会议使用 CoreData 和 iCloud。他们在最后一节的种子主题下讨论了这个问题。他们还提供了一些示例代码，您可以从包含示例的网站获取这些代码。简而言之，您必须打开 2 个持久存储，设置获取大小，然后从源中获取批次，循环遍历它们并将它们添加到新存储中，并以批次大小间隔保存并重置。很简单。