Question

我正在处理我应用的最后一段，这似乎是我遇到问题的最后一部分。无论如何，手指交叉了。

我已经将CoreData全部设置好并准备好在表格中显示（希望，我无法在表格中查看它还有待验证）。

我现在遇到的问题是，当实现CoreData加载的视图时，在启动我的NSManagedObjectContext时会发生致命错误。请注意，我使用两个单独的ViewControllers来获取除TableViewController之外的数据，因此我在我的应用程序中声明了总共3个NSManagedContextObjects - 我不确定这是否是问题。导致它的行在我的viewDidLoad函数中。请参阅下面的代码。

override func viewDidLoad() {
        super.viewDidLoad()

        managedObjectContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    }

我不完全确定如何解决这个问题，因为我正在关注整个过程的教程。

编辑：我将添加受CoreData影响的所有代码，这样可能有助于解决问题。

以下是我的核心数据模型的屏幕截图

的AppDelegate

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?


func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    return true
}

func applicationWillResignActive(_ application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and invalidate graphics rendering callbacks. Games should use this method to pause the game.
}

func applicationDidEnterBackground(_ application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
}

func applicationWillEnterForeground(_ application: UIApplication) {
    // Called as part of the transition from the background to the active state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(_ application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

func applicationWillTerminate(_ application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    // Saves changes in the application's managed object context before the application terminates.
    //self.saveContext()
}

// MARK: - Core Data Stack
lazy var persistentContainer: NSPersistentContainer = {
    /*
     The persistent container for the application. This implementation
     creates and returns a container, having loaded the store for the
     application to it. This property is optional since there are legitimate
     error conditions that could cause the creation of the store to fail.
     */
    let container = NSPersistentContainer(name: "RSDB_1_0_COREDATA")
    container.loadPersistentStores(completionHandler: { (storeDescription, error) in
        if let error = error as NSError? {
            // Replace this implementation with code to handle the error appropriately.
            // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.

            /*
             Typical reasons for an error here include:
             * The parent directory does not exist, cannot be created, or disallows writing.
             * The persistent store is not accessible, due to permissions or data protection when the device is locked.
             * The device is out of space.
             * The store could not be migrated to the current model version.
             Check the error message to determine what the actual problem was.
             */
            fatalError("Unresolved error \(error), \(error.userInfo)")
        }
    })
    return container
}()

// MARK: - Core Data Saving support

func saveContext () {
    let context = persistentContainer.viewContext
    if context.hasChanges {
        do {
            try context.save()
        } catch {
            // Replace this implementation with code to handle the error appropriately.
            // fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            let nserror = error as NSError
            fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
        }
    }
}

}

第一视图控制器

let newInfo = GeneralInfo(context:managedObjectContext1)
        newInfo.courseNumber = studCourse
        newInfo.scenarioNumber = studScen

        do {
            try self.managedObjectContext1.save()
        }catch {
            print("Could not save data \(error.localizedDescription)")
        }


        performSegue(withIdentifier: "segue3", sender: self)

不同的视图控制器

 let newEvaluation = GeneralEvaluation(context:managedObjectContext)
        newEvaluation.idScore = String(ID)
        newEvaluation.washScore = String(WASH)
        newEvaluation.totalScore = String(total)

        do {
            try self.managedObjectContext.save()
        }catch {
            print("Could not save data \(error.localizedDescription)")
        }

        performSegue(withIdentifier: "segue4", sender: self)

TableViewController

let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! TheTableViewCell

   let info = courseInfo[indexPath.row]
   let score = scores[indexPath.row]

    cell.CLASS.text = info.courseNumber
    cell.SCENARIO.text = info.scenarioNumber

    cell.WASH.text = score.washScore
    cell.ID.text = score.idScore
    cell.TOTAL.text = score.totalScore

Answer 1

查看错误消息的文本和堆栈跟踪会很有帮助。

您可以先打破这一系列电话，缩小您崩溃的范围。

let appDelegate = (UIApplication.shared.delegate as! AppDelegate)
let container = appDelegate.persistentContainer
managedObjectContext = container.viewContext

你的堆栈（持久性容器/持久性存储协调器/托管对象模型/托管对象上下文是否在加载视图控制器之前被实例化了？它似乎没有。因为你这么早崩溃，我出去了，并且猜测某个地方有拼写错误或名称不匹配（文件名与您定义的代码中的内容不匹配）。或者您的MOM可能不包含在捆绑包中作为资源？

Answer 2

您似乎在懒惰的var persistentContainer中抛出错误。这很好。这意味着您可以排除视图控制器作为原因。我们能看到Xcode（command-1）文件部分的截图吗？

启动NSManagedObjectContext会产生致命错误？

2 个答案: