ios - CoreData 无法生成 getter 和 setter

Question

我有一个具有手动定义的类。这可以在下面看到。

class NewsFeedResponse: NSManagedObject, Cachable {

    @NSManaged var id: String?
    @NSManaged var cachedAt: Date?
    @NSManaged var featuredArticles: Array<FeaturedArticle>?
    @NSManaged var learningMaterials: Array<LearningMaterial>?

    enum CodingKeys: String, CodingKey {
        case featuredArticles
        case learningMaterials
    }

    override init(entity: NSEntityDescription, insertInto context: NSManagedObjectContext?) {
        super.init(entity: entity, insertInto: context)
    }

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        super.init(entity: NewsFeedResponse.entity(), insertInto: CoreDataManager.shared.getContext())
        do {
            self.cachedAt = Date()
            self.featuredArticles = try container.decode(Array<FeaturedArticle>?.self, forKey: .featuredArticles)
            self.learningMaterials = try container.decode(Array<LearningMaterial>?.self, forKey: .learningMaterials)
        } catch {
            print(error)
        }
    }

    func encode(to encoder: Encoder) throws { }
}

在核心数据模型中，特色文章和学习 Material 在两个方向上都具有一对多关系。如果我将数组更改为集合，这不会崩溃使用集合的唯一问题是它们不像数组那样排序，因此数据的顺序不一致。还值得注意的是，我没有用 @objc 标记该类，因为如果我这样做，该对象似乎不会被持久化，这就是为什么它没有这个标记。

除此之外，每当我运行我的应用程序时，我都会遇到以下崩溃。

2019-08-20 09:51:07.265011+0100 [89304:24860419] [error] error: Property 'featuredArticles' is marked copy on class ‘XXXXX.NewsFeedResponse'.  Cannot generate a copying setter method for NSManagedObject's to-one relationship.
CoreData: error: Property 'featuredArticles' is marked copy on class 'XXXXXXX.NewsFeedResponse'.  Cannot generate a copying setter method for NSManagedObject's to-one relationship.
2019-08-20 09:51:07.265235+0100 XXXXXXX[89304:24860419] -[XXXXXXX.NewsFeedResponse setFeaturedArticles:]: unrecognized selector sent to instance 0x600002d8afd0
2019-08-20 09:51:07.270994+0100 XXXXXXX[89304:24860419] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[XXXXXXX.NewsFeedResponse setFeaturedArticles:]: unrecognized selector sent to instance 0x600002d8afd0'

我不确定如何编写 coredata 提示的这些 setter。

Answer 1

多对关系必须声明为(最好是非可选)Set 或 NSSet

@NSManaged var featuredArticles: Set<FeaturedArticle>
@NSManaged var learningMaterials: Set<LearningMaterial>

如果您需要订单，有以下三个选项:

1. 将两种类型声明为 NSOrderedSet(没有 Swift 等效项)并选中模型中的 Arrangement: Ordered 复选框。
2. 添加计算属性或方法以返回排序数组。
3. 使用适当的谓词和排序描述符获取特定 NewsFeedResponse 的文章和 Material 。