ios - 在 Swift 编程语言中将 NSManagedObject 从一个类传递到另一个类？

Question

我有以下数据库，

我有以下 NSManagedObject 员工类。

导入基金会 导入核心数据

class Employee: NSManagedObject {

    @NSManaged var age: NSNumber
    @NSManaged var firstName: String
    @NSManaged var gender: String
    @NSManaged var lastName: String
    @NSManaged var salary: NSNumber

}

我有一个 UIViewController 类，它包含 5 个 UITextFields 和一个 UIButton，用于在数据库中添加值。

如果我在同一个类中插入值，比如

let employee:Employee = NSEntityDescription.insertNewObjectForEntityForName("Employee", inManagedObjectContext: self.managedObjectContext!) as Employee

它工作正常，但我遵循了应用程序的面向对象结构并制作了一个 DatabaseManager.swift 类，

所以现在我面临的问题是将 NSManagedObject 从 Controller 类传递到 DatabaseManager 类。

我编码如下，但是它给出了错误。

@IBAction func addToDatabase(sender: UIButton) {
    println("Add to Database is clicked")

    var employee:Employee = Employee() //Employee is subclass of NSManagedObject

    employee.firstName = textfield_firstName.text
    employee.lastName = textfield_lastName.text
    employee.gender = textfield_gender.text
    employee.age = (textfield_age.text as String).toInt()!
    employee.salary = (textfield_salary.text as String).toInt()!

    var databaseManager:DatabaseManager = DatabaseManager()
    databaseManager.saveEmployee(employee)

}

错误:

2014-11-06 10:34:46.710 CoreDataWithSwift[588:9220] CoreData: error: Failed to call designated initializer on NSManagedObject class 'CoreDataWithSwift.Employee' 
2014-11-06 10:34:46.736 CoreDataWithSwift[588:9220] -[CoreDataWithSwift.Employee setFirstName:]: unrecognized selector sent to instance 0x7fa269e20800
2014-11-06 10:34:46.756 CoreDataWithSwift[588:9220] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CoreDataWithSwift.Employee setFirstName:]: unrecognized selector sent to instance 0x7fa269e20800'

谢谢。

Answer 1

你不应该直接创建 NSManagedObject 实例，而是调用:

var employee = NSEntityDescription.insertNewObjectForEntityForName(entityName, inManagedObjectContext: managedObjectContext) as Employee?

然后更改员工的属性并保存结果。