Ios NSManagedObject在cellForItemAt indexPath中变为零

我使用水平滚动的collectionView。在viewdidload中，我获取coredata对象

var listOfArticles  = [Article]()

  override func viewDidLoad() {
        super.viewDidLoad()
     listOfArticles =   CoreDataManager().fetchArticleWithCategory(category: "Entertainment", limit: 10)!
}

当我在viewdidload中打印项目列表时

for newData in listOfArticles {
            print(newData.article_id)
        }

输出：-

在indexath.item==0时，我能够获取

Article

objet，但indexath.item==1

Article

objet变为空

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell :NewsCollectionViewCell  = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! NewsCollectionViewCell
        var articles = listOfArticles[indexPath.item]
        cell.currentArticleToShow = articles
        if let newVar = articles.articleToSectionRel?.allObjects {
            cell.currentSections = newVar as! [Section]
        }
    }

当我尝试在indexath.item==0处打印采购订单文章时

输出：

---

为什么在我将数据提取到viewdidload时，Articles对象在object indexPath.item==1处变为null？。提前谢谢

这看起来是正确的。你在索引1的文章是错误的；它还没有被取出来。一旦访问某个属性，核心数据就会将获取转换为实际对象。请尝试

po articles[“article_id”]

更新问题..我在cellForItemAt indexPath的NSMangeObject中没有看到空的objectentity:在indexPath.item=1处的cellForItemAt indexPath中。您正在创建新对象

CoreDataManager（）

希望您的上下文是共享的或全局的，否则您将无法检查我的问题

override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell :NewsCollectionViewCell  = collectionView.dequeueReusableCell(withReuseIdentifier: reuseIdentifier, for: indexPath) as! NewsCollectionViewCell
        var articles = listOfArticles[indexPath.item]
        cell.currentArticleToShow = articles
        if let newVar = articles.articleToSectionRel?.allObjects {
            cell.currentSections = newVar as! [Section]
        }
    }

 <Article: 0x60800009f2c0> (entity: Article; id: 0xd000000000100024 <x-coredata://BA36E40C-6783-4CBF-8C2F-F596ABF1CD56/Article/p4> ; data: {
    articleToSectionRel = "<relationship fault: 0x600000426a00 'articleToSectionRel'>";
    "article_id" = 1599845;
    "book_mark" = 0;
    category = Entertainment;
    "image_url" = "http://images.newindianexpress.com/uploads/user/imagelibrary/2017/4/20/original/KatyPerry-AP1.png";
    "modiffied_date" = "2017-05-01 16:52:00";
    "sub_category" = English;
    summary = "http://images.newindianexpress.com/uploads/user/imagelibrary/2017/4/20/original/KatyPerry-AP1.png";
    title = "Katy Perry courts controversy\U00a0comparing her black hair to Barack Obama";
    topStorie = 0;
})

<Article: 0x608000280370> (entity: <null>; id: 0xd000000000180024 <x-coredata://BA36E40C-6783-4CBF-8C2F-F596ABF1CD56/Article/p6> ; data: <fault>)

  listOfArticles =   CoreDataManager().fetchArticleWithCategory(category: "Entertainment", limit: 10)!