如何映射NSManageBject的模型？

Question

当我尝试执行此操作时，如果我使用上下文，则该模型将存储在NSManageBjectContext中，并且没有它会引发错误，但是我并不期望相同的结果。 有没有简单的方法来实施此功能？

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

    @NSManaged public var word: String?
    @NSManaged public var uuid: UUID?
}

struct WordPresentation {
    let word: String
    let uuid: UUID
}

func mappingNSManagedObject(_ wordPresentation: WordPresentation) -> WordDal {
    let model = WordDal()
    model.uuid = wordPresentation.uuid
    model.word = wordPresentation.word
    return model
}

Answer 1

考虑重新设计您的模型以计算出新的包装器类型的属性，该属性会转换属性值与包装器值的属性值。

在Swift Core数据模型中实施计算的属性通常是实现所需物品的一种清晰，更直观的方法。

这是一个示例实现：

struct WordPresentation {
    let word: String
    let uuid: UUID }

class WordDal: NSManagedObject {
    @nonobjc public class func fetchRequest() -> NSFetchRequest<WordDal> {
        return NSFetchRequest<WordDal>(entityName: "WordDal")
    }
    
    @NSManaged public var word: String?
    @NSManaged public var uuid: UUID?
    
    var wordPresentation : WordPresentation {
        get {
            return WordPresentation(word: self.word, uuid: self.uuid)
        }
        set {
            self.word = newValue.name
            self.uuid = newValue.id
        }
    } 
}

Answer 2

我解决了这样的问题（我不知道为什么要推迟它并且不立即理解）：

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

    @NSManaged public var word: String?
    @NSManaged public var uuid: UUID?
}

struct WordPresentation {
    let word: String
    let uuid: UUID
}

func removeFromStorage(by uuid: UUID) {
    getDataFromStorage { [weak self] objects  in
        guard let self = self else { return }
        if let objectForRemove = objects.first(where: { $0.uuid == uuid }) {
        self.coreDataStack.mainContext.delete(objectForRemove)
        self.coreDataStack.saveContext(self.managedObjectContext)
        }
    }
}

我正在使用UUID创建演示级模型！
我只删除他自己。
现在我可以双向行走。