ios - Core Data 对子数组 NSSet 进行排序

Question

我尝试对实体内的数组 (vociMenu: NSSet) 进行排序，但收到此错误:

'NSInvalidArgumentException', reason: 'to-many key not allowed here'

这是我的代码:实体

extension SezioniMenu {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<SezioniMenu> {
        return NSFetchRequest<SezioniMenu>(entityName: "SezioniMenu");
    }

    @NSManaged public var sezione: String?
    @NSManaged public var language: Language?
    @NSManaged public var vociMenu: NSSet? <---- /// I MUST ORDER THIS ENTITY

}

查询

        let fetchRequest: NSFetchRequest<SezioniMenu> = SezioniMenu.fetchRequest()
                                fetchRequest.returnsObjectsAsFaults = false

        let sortDescriptor = NSSortDescriptor(key: "vociMenu.tipologia", ascending: true)

        let sortDescriptors = [sortDescriptor]
        let predicate = NSPredicate(format: "language.code = %@", Singleton.sharedInstance.linguaDispositivo)

        fetchRequest.predicate = predicate
        fetchRequest.sortDescriptors = sortDescriptors
    do {
                array = try self.managedObjectContext.fetch(fetchRequest)
   .....

如何订购实体“vociMenu: NSSet”？

感谢您的帮助

更新

我设法通过这种方式解决我的情况。直接在TableView的委托(delegate)中对列表进行排序:

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
       let cell : CustomTableViewCell = tableView.dequeueReusableCell(withIdentifier: "cell") as! CustomTableViewCell
       ///For each section retrieve the list to order
       let list = self.listSezioni?[indexPath.section].vociMenu?.allObjects as! [VociMenu]
       ///I run the sort (sort) of the items
       var listSort = list.sorted(by: { $0.tipologia! < $1.tipologia! })

       cell.labelMenu.text = listSort[indexPath.row].tipologia
}

Answer 1

我不知道您的 vociMenu.tipologia 字段的类型是什么，但问题可能出在使用 keyPathes 而不仅仅是键上。尝试使用 sortDescriptor，而不是由

创建

public init(key: String?, ascending: Bool, comparator cmptr: @escaping Foundation.Comparator)

您可以在其中明确提供比较逻辑。希望这有帮助