ios - returnsObjectsAsFaults 未按预期工作

Question

我创建了一个核心数据对象如下:

@objc(Gates)
public class Gates : NSManagedObject {

    public class func getFetchRequest() -> NSFetchRequest<Gates> {
        let request = NSFetchRequest<Gates>(entityName: "Gates")
        request.returnsObjectsAsFaults = false
        return request
    }

    @NSManaged var updatedAt: String
    @NSManaged var objectId: String
    @NSManaged var identifier: String
    @NSManaged var name: String
    @NSManaged var address: String
    @NSManaged var dueDate: String
    @NSManaged var productionCode: String
    @NSManaged var locationCountry: String
    @NSManaged var locationCity: String
    @NSManaged var locationBuilding: String
    @NSManaged var locationLevel: String
    @NSManaged var locationRoom: String
    @NSManaged var locationRange: String
    @NSManaged var isFavorite: Bool

    public func setGateData(gateDict: [String: Any]) {
        updatedAt = gateDict["updatedAt"] as? String ?? ""
        objectId = gateDict["objectId"] as? String ?? ""
        identifier = gateDict["identifier"] as? String ?? ""
        name = gateDict["name"] as? String ?? ""
        isFavorite = gateDict["isFavorite"] as? Bool ?? false
        address = gateDict["address"] as? String ?? ""
        dueDate = gateDict["dueDate"] as? String ?? ""
        productionCode = gateDict["productionCode"] as? String ?? ""
        locationCountry = gateDict["locationCountry"] as? String ?? ""
        locationCity = gateDict["locationCity"] as? String ?? ""
        locationBuilding = gateDict["locationBuilding"] as? String ?? ""
        locationLevel = gateDict["locationLevel"] as? String ?? ""
        locationRoom = gateDict["locationRoom"] as? String ?? ""
        locationRange = gateDict["locationRange"] as? String ?? ""
    }
}

我还在 xcdatamodeld 中进行了设置:

现在，在我将对象保存到核心数据中并使用 getFetchRequest() 之后作为设置的类的一部分的方法 request.returnsObjectsAsFaults = false在 request 上但是当我尝试打印获取的对象时，我仍然得到以下结果:

 <Gates: 0x60c0000959a0> (entity: Gates; id: 0xd000000005e40000 <x-
 coredata://B9C33A5D-BF96-433A-9186-F51AA253F488/Gates/p377> ; data: <fault>)

如您所见，在这种情况下，数据仍然是 data: <fault> .

为什么即使我设置了 request.returnsObjectsAsFaults = false 也没有检索到对象参数？我错过了什么？

Answer 1

我遇到了这个问题，我发现在我的案例中我没有使用行中的对象值，而是先用它初始化一个变量然后使用该变量。

我很想知道这是 Core Data 错误还是我做错了什么。

public class Person: NSManagedObject, Identifiable {
    @NSManaged public var firstName: String
    @NSManaged public var lastName: String
    @NSManaged public var emailAddress: String
}

这并不总是有效:

CoreDataManager.shared.persistentContainer.performBackgroundTask{ context in
    context.automaticallyMergesChangesFromParent = true
    context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
    
    do {
        let email = "123Tester@gmail.com"
        let request = Person.getPersonWith(email: email)
        request.returnsObjectsAsFaults = false //DOES NOT WORK
        
        if let person = try context.fetch(request).first{
            print(person.fullName)
        }
    } catch{
        fatalError()
    }
}

但是这样

CoreDataManager.shared.persistentContainer.performBackgroundTask{ context in
    context.automaticallyMergesChangesFromParent = true
    context.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy
    
    do {
        let email = "123Tester@gmail.com"
        let request = Person.getPersonWith(email: email)
        
        if let person = try context.fetch(request).first{
            let fullName = person.fullName
            print(fullName)
        }
    } catch{
        fatalError()
    }
}