如何正确使用嵌套类型编写数据模型或在Swift中使用CoreData

import CoreData

class DataManager {
    // 定义嵌套类型，用于管理数据模型
    enum Model {
        // 定义实体名称
        static let entityName = "Person"
        
        // 定义实体属性
        enum Attribute {
            static let name = "name"
            static let age = "age"
        }
    }
    
    // 创建数据模型对象
    func createPerson(name: String, age: Int) {
        guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
            return
        }
        
        let managedContext = appDelegate.persistentContainer.viewContext
        let entity = NSEntityDescription.entity(forEntityName: Model.entityName, in: managedContext)!
        let person = NSManagedObject(entity: entity, insertInto: managedContext)
        
        person.setValue(name, forKey: Model.Attribute.name)
        person.setValue(age, forKey: Model.Attribute.age)
        
        do {
            try managedContext.save()
        } catch let error as NSError {
            print("Could not save. \(error), \(error.userInfo)")
        }
    }
    
    // 查询数据模型对象
    func fetchPersons() -> [NSManagedObject]? {
        guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
            return nil
        }
        
        let managedContext = appDelegate.persistentContainer.viewContext
        let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: Model.entityName)
        
        do {
            let persons = try managedContext.fetch(fetchRequest)
            return persons
        } catch let error as NSError {
            print("Could not fetch. \(error), \(error.userInfo)")
            return nil
        }
    }
}