Ios 当我将托管对象上下文分配给变量时，我的应用程序正在崩溃

请帮忙。我正在制作这个应用程序，一开始我没有添加coreData。我后来在一些在线教程的帮助下添加了它。除了我的应用程序在第33行崩溃之外，一切似乎都很正常：

import UIKit
import CoreData

class SittingsViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        //preperation
        Stepper.continuous = false
        Stepper.autorepeat = false
        Stepper.maximumValue = 6
        Stepper.minimumValue = 0
        valChanged(1)
        var request = NSFetchRequest(entityName: "Sittings")
        request.returnsObjectsAsFaults = false
        Stepper.value = managedContext.executeFetchRequest(request, error: nil) as! Double
        managedContext.save(nil)
}

//global vars and iboutlets
@IBOutlet var Stepper: UIStepper!
@IBOutlet var AproximateLabel: UILabel!
var decimalPlaces = Int()
    //core data
    var appDel = UIApplication.sharedApplication().delegate as! AppDelegate
    var managedContext = SittingsViewController().appDel.managedObjectContext! //my error happens here
    let entity =  NSEntityDescription.entityForName("Sittings",
        inManagedObjectContext:
        SittingsViewController().managedContext)
    let decimal = NSManagedObject(entity: SittingsViewController().entity!,
        insertIntoManagedObjectContext:SittingsViewController().managedContext)


@IBAction func stepperValueChanged(sender: UIStepper) {
    valChanged(Int(sender.value))
    AproximateLabel.text = Int(sender.value).description
}

//segue
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        var firstView: ViewController = segue.destinationViewController as! ViewController
        firstView.decimalPlaces = Int(decimalPlaces)
}

func valChanged(num: Int) {
    let entity =  NSEntityDescription.entityForName("Sittings",
        inManagedObjectContext:
        managedContext)
    let decimal = NSManagedObject(entity: entity!,
        insertIntoManagedObjectContext:managedContext)

    //3
    decimal.setValue(num, forKey: "decimalPlaces")

    //4
    var error: NSError?
    if !managedContext.save(&error) {
        println("Could not save \(error), \(error?.userInfo)")
    }  
    decimalPlaces = num
}
}

如果您需要更多的代码或其他任何东西，我将很乐意帮助

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回溯：

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AppDelegate：

导入UIKit 导入CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

var window: UIWindow?

func application(application: UIApplication, didFinishLaunchingWithOptions     launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    UIApplication.sharedApplication().statusBarStyle =     UIStatusBarStyle.LightContent
    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 throttle down OpenGL ES frame rates. 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 inactive 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:.
    self.saveContext()
}

// MARK: - Core Data stack

lazy var applicationDocumentsDirectory: NSURL = {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "com.xxxx.math" in the application's documents Application Support directory.
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    return urls[urls.count-1] as! NSURL
    }()

lazy var managedObjectModel: NSManagedObjectModel = {
    // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
    let modelURL = NSBundle.mainBundle().URLForResource("math", withExtension: "momd")!
    return NSManagedObjectModel(contentsOfURL: modelURL)!
    }()

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added 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.
    // Create the coordinator and store
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("math.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
        coordinator = nil
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        // Replace this with code to handle the error appropriately.
        // abort() 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.
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort()
    }

    return coordinator
    }()

lazy var managedObjectContext: NSManagedObjectContext? = {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
    let coordinator = self.persistentStoreCoordinator
    if coordinator == nil {
        return nil
    }
    var managedObjectContext = NSManagedObjectContext()
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
    }()

// MARK: - Core Data Saving support

func saveContext () {
    if let moc = self.managedObjectContext {
        var error: NSError? = nil
        if moc.hasChanges && !moc.save(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() 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.
            NSLog("Unresolved error \(error), \(error!.userInfo)")
            abort()
        }
    }
}
}

多谢各位

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我刚刚发现我的managedObjectContext为零，但我不知道为什么？

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有人能帮忙吗？

请发布完整的回溯。好的@JAL，我添加了回溯。你能帮忙吗。我还添加了appDelegate。有人能帮我吗？你为什么要从

SittingsViewController（）获取它。appDel.managedObjectContext而不仅仅是
appDel.managedObjectContext，您在前一行中声明了它？我一定会在回家@Bek时尝试。非常感谢：-D！