我是Swift的新手，我正在尝试学习如何使用Core Data。但我遇到了这个错误，我不确定我做错了什么。我在网上搜索并尝试了一些方法，但我无法找到正确的方法。

Failed to call designated initializer on NSManagedObject class 'FirstCoreData.Course'

当执行此行时：

ncvc.currentCourse = newCourse

在此函数中：

class TableViewController: UITableViewController, AddCourseViewControllerDelegate {

var managedObjectContext = NSManagedObjectContext.init(concurrencyType: NSManagedObjectContextConcurrencyType.MainQueueConcurrencyType)

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "addCourse" {
        let ncvc = segue.destinationViewController as! NewCourseViewController
        ncvc.delegate = self

        let newCourse = NSEntityDescription.insertNewObjectForEntityForName("Course", inManagedObjectContext: self.managedObjectContext) as! Course
        ncvc.currentCourse = newCourse

    }
}

由“创建NSManagedObject子类...”为课程实体生成的类：

import Foundation
import CoreData

class Course: NSManagedObject {

// Insert code here to add functionality to your managed object subclass

}

还有：

import Foundation
import CoreData

extension Course {

    @NSManaged var title: String?
    @NSManaged var author: String?
    @NSManaged var releaseDate: NSDate?

}