Question

我有一个具有手动定义的类。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 { }
}

featureArticles和learningMaterials在coredata模型中的两个方向上都具有一对多的关系。如果将Array更改为Set，这不会导致使用Set的唯一问题是它们的排列顺序不像Arrays，因此数据顺序不一致。值得注意的是，我没有用@objc标记该类，因为如果我这样做，该对象似乎就不会持久保存，这就是为什么它没有此标记的原因。

此外，每当我现在运行应用程序时，都会发生以下崩溃。

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抱怨的这些设置方法。

Answer 1

对多关系必须声明为（最好是非可选的）Set或NSSet

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

如果您需要订单，则有以下三种选择：

将两种类型都声明为NSOrderedSet（没有Swift等效项），然后选中模型中的排列：已排序复选框。
添加计算属性或方法以返回排序后的数组。
使用适当的谓词和排序描述符获取特定NewsFeedResponse的文章和材料。

CoreData无法生成getter和setter

1 个答案: