IOS-无法强制转换NSKnownKeyDictionary1类型的值

我需要

区分

一个

字段

如下：

func fetchListLanguagesContentDegreesPage(catId: Int64,
                                          locale: String,
                                          completionHandler: @escaping (() throws -> [Degrees]) -> Void) {
    privateManagedObjectContext.perform {
        do {
            let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Degrees")
            let query = NSPredicate(format: "(%K = %@) AND (%K = %@)",
                                    "locale",locale,
                                    "parentID",String(catId))
            fetchRequest.predicate = query
            fetchRequest.resultType = NSFetchRequestResultType.dictionaryResultType
            fetchRequest.propertiesToFetch = ["langName"]
            fetchRequest.returnsDistinctResults = true
            let results = try self.privateManagedObjectContext.fetch(fetchRequest) as! [Degrees]
            completionHandler{return results}
        } catch {
            completionHandler { throw DegreesStoreError.CannotFetch("Cannot fetch orders") }
        }
    }
}

我能做什么？我如何才能转换NSKnownKeyDictionary1

Could not cast value of type 'NSKnownKeysDictionary1' to 'PortalAlmostafaApp.Degrees'