ios - 具有核心数据和 Restkit 的多 View Controller

Question

我想我可能在这里遗漏了一些明显的东西，因为这一定是 RestKit 的一个非常常见的用例。

我想要两个 View Controller ，每个都只是将 NSFetchedResultsController 粘附到 UITableView，假设第一个显示帖子的时间轴，第二个显示特定用户的帖子列表。 我需要为每个 View Controller 提供不同的帖子列表，但我不知道如何使用 RestKit 获取这些列表。

目前，我在每个 View 上使用相同的 NSManagedObjectContext，这意味着如果我有一个帖子存在于 View Controller B 但不在 View Controller A 中，如果我在加载 View Controller B 后返回 View Controller A，那对 View Controller B 来说应该是唯一的帖子现在也显示在 View Controller A 中。

我想我应该做的是为每个 View 使用不同的 NSManagedObjectContexts，共享一个 RKManagedObjectStore，但我不知道如何让它工作。

这些是我的映射:

RKEntityMapping *userMapping = [RKEntityMapping mappingForEntityForName:@"User" inManagedObjectStore:managedObjectStore];
[userMapping addAttributeMappingsFromDictionary:@{
    @"avatar_url": @"avatarURL",
    @"id":         @"userID",
    @"first_name": @"firstName",
    @"last_name":  @"lastName",
    @"username":   @"username"
}];
userMapping.identificationAttributes = @[@"userID"];

RKEntityMapping *postMapping = [RKEntityMapping mappingForEntityForName:@"Post" inManagedObjectStore:managedObjectStore];
[postMapping addAttributeMappingsFromDictionary:@{
    @"id":          @"postID",
    @"content_url": @"contentURL",
    @"created_at":  @"createdAt"
}];
postMapping.identificationAttributes = @[@"postID"];
[postMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"creator" toKeyPath:@"creator" withMapping:userMapping]];

[userMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"posts" toKeyPath:@"posts" withMapping:postMapping]];

[objectManager.router.routeSet addRoute:[RKRoute routeWithClass:[Post class] pathPattern:@"/posts\\.json" method:RKRequestMethodGET]];
[objectManager.router.routeSet addRoute:[RKRoute routeWithClass:[Post class] pathPattern:@"/posts\\.json" method:RKRequestMethodPOST]];

[objectManager addResponseDescriptor:[RKResponseDescriptor responseDescriptorWithMapping:postMapping
                                                                             pathPattern:@"/posts.json"
                                                                                 keyPath:nil
                                                                             statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)]];

[objectManager addResponseDescriptor:[RKResponseDescriptor responseDescriptorWithMapping:userMapping
                                                                             pathPattern:@"/_/:username.json"
                                                                                 keyPath:nil
                                                                             statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)]];

These are my Core Data entities

(StackOverflow 不允许我发布图片……)

在我的 View Controller 中，这是我的fetchedResultsController getter

- (NSFetchedResultsController *)fetchedResultsController
{
    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Post" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    // Edit the sort key as appropriate.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createdAt" ascending:NO];
    NSArray *sortDescriptors = @[sortDescriptor];

    [fetchRequest setSortDescriptors:sortDescriptors];

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"Master"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error]) {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _fetchedResultsController;
}

这就是我从时间线 View Controller 发出请求的方式

[[RKObjectManager sharedManager] getObjectsAtPath:@"/posts.json" parameters:nil success:success failure:failure];
// The success and failure blocks don't do all that much, so I've just left them out.

这就是我向用户 View Controller 发出请求的方式

NSString *path = [NSString stringWithFormat:@"/_/%@.json", self.user.username];
[[RKObjectManager sharedManager] getObjectsAtPath:path parameters:nil success:success failure:failure];

Answer 1

首先，不要以/ 开始路径模式。您也不需要在请求路径的开头使用它。

对于实际问题，当您定义NSFetchedResultsController 时，您还需要为fetchRequest 定义一个NSPredicate。这个谓词将允许 FRC 仅过滤 View Controller 实际感兴趣的信息(即使您的数据模型实际上包含比这更多的数据)。谓词将基于 Controller 传递的某个值，它应该显示...的详细信息

检查谓词文档 here .