iOS 8核心数据堆栈 – 致命错误：在解包可选值时发现为零

概述我对iOS开发相对较新,决定实现自己的Core Data堆栈,取代Apple的默认堆栈. 我必须在我的代码中进行更改(显然)并且能够解决它,但是在这种情况下我不能.这是我的代码： import UIKitimport CoreDataclass AddTableViewController: UITableViewController, UIImagePickerControllerDele 我对iOS开发相对较新,决定实现自己的Core Data堆栈,取代Apple的默认堆栈.

我必须在我的代码中进行更改(显然)并且能够解决它,但是在这种情况下我不能.这是我的代码：

import UIKitimport CoreDataclass AddtableVIEwController: UItableVIEwController,UIImagePickerControllerDelegate,UINavigationControllerDelegate {    @IBOutlet weak var nameTextFIEld:UITextFIEld!    @IBOutlet weak var locationTextFIEld:UITextFIEld!    @IBOutlet weak var imageVIEw:UIImageVIEw!    @IBOutlet weak var notesVIEw:UITextVIEw!    var coreDataStack = (UIApplication.sharedApplication().delegate as AppDelegate).coreDataStack    var backpackerSpot:BackpackerSpot!    var managedContext: NSManagedobjectContext!    overrIDe func vIEwDIDLoad() {        super.vIEwDIDLoad()    }    overrIDe func dIDReceiveMemoryWarning() {        super.dIDReceiveMemoryWarning()        // dispose of any resources that can be recreated.    }    // Todo Give user the choice of the Photo library or the Camera    overrIDe func tableVIEw(tableVIEw: UItableVIEw,dIDSelectRowAtIndexPath indexPath: NSIndexPath) {        if indexPath.row == 0 {            if UIImagePickerController.isSourceTypeAvailable(.Camera) {                let imagePicker = UIImagePickerController()                imagePicker.allowsEditing = false                imagePicker.delegate = self                imagePicker.sourceType = .Camera                self.presentVIEwController(imagePicker,animated: true,completion: nil)            }        }        tableVIEw.deselectRowAtIndexPath(indexPath,animated: true)    }    // FIXME image is being displayed in landscape if it is taken in portrait mode by default    func imagePickerController(picker: UIImagePickerController!,dIDFinishPickingImage image: UIImage!,editingInfo: [NSObject : AnyObject]!) {        imageVIEw.image = image        imageVIEw.contentMode = UIVIEwContentMode.ScaleAspectFill        imageVIEw.clipsToBounds = true        dismissVIEwControllerAnimated(true,completion: nil)    }    @IBAction func save() {        //valIDation        var errorFIEld = ""        // Todo have placeholder text in the NOTES fIEld match up with the placholder text in the name and LOCATION fIElds.        if nameTextFIEld.text == "" {            errorFIEld = "name"        } else if locationTextFIEld.text == "" {            errorFIEld = "location"        } else if notesVIEw.text == "" {            errorFIEld = "notes"        }        if errorFIEld != "" {            let alertController = UIAlertController(Title: "Error",message: "You must fill in \(errorFIEld).",preferredStyle: .Alert)            let doneAction = UIAlertAction(Title: "OK",style: .Default,handler: nil)            alertController.addAction(doneAction)            self.presentVIEwController(alertController,completion: nil)            return        }        // If all fIElds are correctly filled in,extract the fIEld value        // Create Restaurant Object and save to data store//        if let managedobjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).coreDataStack.context {            let entityBackpackerSpot = NSEntityDescription.entityForname("BackpackerSpot",inManagedobjectContext: coreDataStack.context)            backpackerSpot?.spotname = nameTextFIEld.text            backpackerSpot?.spotLocation = locationTextFIEld.text            backpackerSpot?.spotimage = UIImagePNGRepresentation(imageVIEw.image)            backpackerSpot?.spotNote = notesVIEw.text            var error: NSError?            if !managedContext.save(&error) {                println("insert error: \(error!.localizedDescription)")                return            }        // Execute the unwind segue and go back to the home screen        performSegueWithIDentifIEr("unwindToHomeScreen",sender: self)    }}

该应用程序启动正常,但是当我点击附加到保存功能的UIbutton时,它崩溃了,我收到以下错误：

Fatal error: unexpectedly found nil while unwrapPing an Optional value(lldb)

调试器突出显示的行是：

if !managedContext.save(&error) {

不可否认,我必须花更多时间在Swift中使用Optionals,因为它们似乎常常给我带来麻烦,尽管通常我能够弄明白.如果有人能指出我正确的方向,这将是伟大的.谢谢.

编辑：这是我的核心数据栈：

import Foundationimport CoreDataclass CoreDataStack {    let model: NSManagedobjectModel    let storeCoordinator: NSPersistentStoreCoordinator    let context: NSManagedobjectContext    let store: NSPersistentStore?    let dbname = "BackpackerSpots"    // these options do the migration for us    let options = [NSInferMapPingModelautomaticallyOption:true,NSMigratePersistentStoresautomaticallyOption: true]    init() {        //1 loading model from the file        let bundle = NSBundle.mainBundle()        let modelURL = bundle.URLForResource(dbname,withExtension: "momd")        model = NSManagedobjectModel(contentsOfURL: modelURL!)!        //2 store coordinator created using that model        storeCoordinator = NSPersistentStoreCoordinator(managedobjectModel: model)        //3 context        context = NSManagedobjectContext()        context.persistentStoreCoordinator = storeCoordinator        //4. store        let documentsURL = MydocumentDirectory()        let storeURL = documentsURL.URLByAppendingPathComponent(dbname)        var error:NSError?        store = storeCoordinator.addPersistentStoreWithType(NSsqliteStoreType,configuration: nil,URL: storeURL,options: nil,error: &error)        if store == nil {            println("error adding persistent store: \(error)")            abort()        }    }    func saveContext() {        var error: NSError?        if context.hasChanges && !context.save(&error) {            println("Could not save. \(error),\(error?.description)")        }    }}

编辑：这是我的根视图控制器：

import UIKitimport CoreDataclass BackpackerSpottableVIEwController: UItableVIEwController,NSFetchedResultsControllerDelegate {    var coreDataStack = (UIApplication.sharedApplication().delegate as AppDelegate).coreDataStack//    var backpackerSpot:BackpackerSpot!    var managedContext: NSManagedobjectContext!    var backpackerSpots:[BackpackerSpot] = []    var fetchResultController:NSFetchedResultsController!    // Let's add some animations!    overrIDe func tableVIEw(tableVIEw: UItableVIEw,willdisplayCell cell: UItableVIEwCell,forRowAtIndexPath indexPath: NSIndexPath) {        // initial cell state        cell.Alpha = 0        // state after animations        UIVIEw.animateWithDuration(1.0,animations: { cell.Alpha = 1})    }    overrIDe func vIEwDIDLoad() {        super.vIEwDIDLoad()        var fetchRequest = NSFetchRequest(entityname: "BackpackerSpot")        let sortDescriptor = NSSortDescriptor(key: "spotname",ascending: true)        fetchRequest.sortDescriptors = [sortDescriptor]//        if let managedobjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).coreDataStack {        let entityBackpackerSpot = NSEntityDescription.entityForname("BackpackerSpot",inManagedobjectContext: coreDataStack.context)            fetchResultController = NSFetchedResultsController(fetchRequest: fetchRequest,managedobjectContext: coreDataStack.context,sectionnameKeyPath: nil,cachename: nil)            fetchResultController.delegate = self            var error: NSError?            var result = fetchResultController.performFetch(&error)            backpackerSpots = fetchResultController.fetchedobjects as [BackpackerSpot]            if result != true {                println(error?.localizedDescription)            }        }    overrIDe func dIDReceiveMemoryWarning() {        super.dIDReceiveMemoryWarning()        // dispose of any resources that can be recreated.    }    // MARK: - table vIEw data source    overrIDe func tableVIEw(tableVIEw: UItableVIEw,numberOfRowsInSection section: Int) -> Int {        return self.backpackerSpots.count    }    overrIDe func tableVIEw(tableVIEw: UItableVIEw,cellForRowAtIndexPath indexPath: NSIndexPath) -> UItableVIEwCell {        let cellIDentifIEr = "Cell"        let cell = tableVIEw.dequeueReusableCellWithIDentifIEr(cellIDentifIEr,forIndexPath: indexPath) as CustomtableVIEwCell        let backpackerSpot = backpackerSpots[indexPath.row]        cell.nameLabel.text = backpackerSpot.spotname        cell.thumbnailImageVIEw.image = UIImage(data: backpackerSpot.spotimage)        cell.locationLabel.text = backpackerSpot.spotLocation        return cell    }    overrIDe func tableVIEw(tableVIEw: UItableVIEw,commitEditingStyle editingStyle: UItableVIEwCellEditingStyle,forRowAtIndexPath indexPath: NSIndexPath) {    }    overrIDe func tableVIEw(tableVIEw: UItableVIEw,editactionsForRowAtIndexPath indexPath: NSIndexPath) -> [AnyObject]? {        var deleteAction = UItableVIEwRowAction(style: UItableVIEwRowActionStyle.Default,Title: "Delete",handler: {            (action:UItableVIEwRowAction!,indexPath:NSIndexPath!) -> VoID in//            if let managedobjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedobjectContext {           let entityBackpackerSpot = NSEntityDescription.entityForname("BackpackerSpot",inManagedobjectContext: self.coreDataStack.context)                let backpackerSpottoDelete = self.fetchResultController.objectAtIndexPath(indexPath) as BackpackerSpot                self.managedContext.deleteObject(backpackerSpottoDelete)                var error: NSError?                if !self.managedContext.save(&error) {                    println("Could not save \(error),\(error?.description)")                }        })        deleteAction.backgroundcolor = UIcolor(red: 169.0/255.0,green: 37.0/255.0,blue:            50.0/255.0,Alpha: 1.0)        return [deleteAction]    }    func controllerWillChangeContent(controller: NSFetchedResultsController!) {        tableVIEw.beginUpdates()    }    func controller(controller: NSFetchedResultsController!,dIDChangeObject anObject: AnyObject!,atIndexPath indexPath: NSIndexPath!,forChangeType type: NSFetchedResultsChangeType,newIndexPath: NSIndexPath!) {        switch type {        case .Insert:            tableVIEw.insertRowsAtIndexPaths([newIndexPath],withRowAnimation: .Fade)        case .Delete:            tableVIEw.deleteRowsAtIndexPaths([indexPath],withRowAnimation: .Fade)        case .Update:            tableVIEw.reloadRowsAtIndexPaths([indexPath],withRowAnimation: .Fade)        default:            tableVIEw.reloadData()        }        backpackerSpots = controller.fetchedobjects as [BackpackerSpot]    }    func controllerDIDChangeContent(controller: NSFetchedResultsController!) {        tableVIEw.endUpdates()    }    overrIDe func prepareForSegue(segue: UIStoryboardSegue,sender: AnyObject!) {        if segue.IDentifIEr == "showBackpackerSpotDetails" {            if let row = tableVIEw.indexPathForSelectedRow()?.row {                let destinationController = segue.destinationVIEwController as DetailVIEwController                destinationController.backpackerSpot = backpackerSpots[row]            }        }    }    @IBAction func unwindToHomeScreen(segue: UIStoryboardSegue) {    }}

解决方法 您尚未初始化NSManagedContext变量.使用默认的Core Data设置,您可以执行以下 *** 作：

overrIDe func vIEwDIDLoad() {      if let appDelegate = UIApplication.sharedApplication().delegate as? AppDelegate {          managedContext = appDelegate.managedobjectContext      } }

编辑：鉴于您的核心数据设置,您应该这样做：

overrIDe func vIEwDIDLoad() {      managedContext = coreDataStack.context }

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