无法执行收集与非集合对象评估

Question

当我执行我赛格瑞通过所有季节从选定放映到下一个视图控制器。

class ShowsViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Request Items with type = Movie
        let request: NSFetchRequest<TelevisionShow> = TelevisionShow.fetchRequest()
        allShows = try! CoreDataStack.context.fetch(request)
        allShows = allShows.sorted(by: { $0.title! <  $1.title! })
    }

    @IBOutlet private weak var collectionView: UICollectionView!
}

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        // Create a variable that you want to send based on the destination view controller

        selectedShow = allShows[indexPath.item]

        // This will perform the segue and pre-load the variable for you to use
        self.performSegue(withIdentifier: "toSeasonsViewController", sender: self)

    }

如果我尝试用NSPredicate一个读取请求时，我得到崩溃。 （2019年2月4日11：10：48.766456 + 0100 TV [16295：659978] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Can't perform collection evaluate with non-collection object.')

class SeasonsViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let request: NSFetchRequest<Season> = Season.fetchRequest()
        request.returnsObjectsAsFaults = false
        request.predicate = NSPredicate(format: "SUBQUERY(televisionShow, $m, ANY $m.seasons IN %@).@count > 0",(pTelevisionShow?.seasons)!)

        allSeasons = try! CoreDataStack.context.fetch(request)
        allSeasons = allSeasons.sorted(by: { $0.number! <  $1.number! })
    }

    @IBOutlet private weak var collectionView: UICollectionView!

    var pTelevisionShow: TelevisionShow?
}

qazxsw POI的问题是，我第一次选择的电视节目，并执行SEGUE，它工作得很好，如果我回去，并选择另一tvshow，它抛出这个错误。

+

pTelevisionShow？.seasons是NSOrderedSet

class AppDelegate: UIResponder, UIApplicationDelegate { Thread 1: signal SIGABRT

libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

解决方案：

Answer 1

***终止应用程序由于未捕获的异常“NSInternalInconsistencyException”，理由是：“不能与非集合对象进行收集评估。”）

看起来像你的谓词返回一个对象，而不是对象的集合。

所以，你的谓词逻辑allSeasons = pTelevisionShow?.seasons!.sorted(by: { ($0 as! Season).number! < ($1 as! Season).number! }) as! [Season] 正在恢复由于某种原因，一个单一的元素。

然而，在你的情况，因为你传递NSPredicate(format: "SUBQUERY(televisionShow, $m, ANY $m.seasons IN %@).@count > 0",(pTelevisionShow?.seasons)!)前进，你的结构已经参照所需pTelevisionShow数据集，并可以直接访问，这样你就不会再需要在seasons一个fetchRequest。

---

删除以下代码：

Season

改变和保持：

let request: NSFetchRequest<Season> = Season.fetchRequest()
request.returnsObjectsAsFaults = false
request.predicate = NSPredicate(format: "SUBQUERY(televisionShow, $m, ANY $m.seasons IN %@).@count > 0",(pTelevisionShow?.seasons)!)