ios - 并非所有单元格都加载到表格 View 中，而是出现空白屏幕。 Xcode/Swift

Question

我能够添加所有核心数据并保存它，甚至将其全部打印到日志中。然而，当我尝试获取核心数据并将其加载到表格 View 时，只有前几个单元格实际加载，而加载单元格下方的所有内容都只是一个空白屏幕。

这是我的 View Controller :

class MasterViewController: UITableViewController, NSFetchedResultsControllerDelegate {

var loggedIn = false

var managedObjectContext: NSManagedObjectContext? = nil
var detailViewController: DetailViewController? = nil

@IBOutlet var tableViewLoginButton: UIBarButtonItem!

@IBAction func tableViewLoginButtonAction(sender: AnyObject) {

    shouldPerformSegueWithIdentifier("loginSegue", sender: nil)

}


override func shouldPerformSegueWithIdentifier(identifier: String?, sender: AnyObject?) -> Bool {

    if let ident = identifier {

        if ident == "loginSegue" {


            if loggedIn == true {

                PFUser.logOutInBackgroundWithBlock({ (error) -> Void in

                    self.checkForUser()

                })


                return false
            }

        }

    }
    return true
}


func checkForUser() {

    let currentUser = PFUser.currentUser()
    if (currentUser != nil) {

        loggedIn = true
        tableViewLoginButton.title = "Logout"

    } else {

        loggedIn = false
        tableViewLoginButton.title = "Login"

    }

}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    // Code for Login and Sign Up

    checkForUser()

    coreDataSetup()


}

func coreDataSetup() {

    // Code for fetching json data, saving as core data and loading to table view

    let appDel: AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate

    let context : NSManagedObjectContext = appDel.managedObjectContext

    let url = NSURL(string: "https://www.kimonolabs.com/api/6tewont8?apikey=CPMj8n9tabsEUqUjKEPiHOmVir5gZjfq")

    let session = NSURLSession.sharedSession()

    let task = session.dataTaskWithURL(url!) { (data, response, error) -> Void in

        if error != nil {

            print(error)

        } else {

            // print(NSString(data: data!, encoding: NSUTF8StringEncoding))

            do {

                let jsonResult = try NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers) as! NSDictionary

                if jsonResult.count > 0 {

                    if let results = jsonResult["results"] as? NSDictionary {

                        if let eventData = results["collection1"] as? NSArray {

                            let request = NSFetchRequest(entityName: "ForumEvents")

                            request.returnsObjectsAsFaults = false

                            do {

                                let results = try context.executeFetchRequest(request)

                                if results.count > 0 {

                                    for result in results {

                                        context.deleteObject(result as! NSManagedObject)

                                        do { try context.save() } catch {}

                                    }

                                }

                            } catch {}

                            for event in eventData {

                                if let eventTitle = event["EventTitle"] as? NSDictionary {

                                    if let eventTitleText = eventTitle["text"] as? String {

                                        if let eventDate = event["EventDate"] as? String {

                                            if let eventTicketLink = event["EventTicketLink"] as? NSDictionary {

                                                if let eventLink = eventTicketLink["href"] as? String {

                                                    let newEvent : NSManagedObject = NSEntityDescription.insertNewObjectForEntityForName("ForumEvents", inManagedObjectContext: context)

                                                    newEvent.setValue(eventTitleText, forKey: "eventTitle")

                                                    newEvent.setValue(eventDate, forKey: "eventDate")

                                                    newEvent.setValue(eventLink, forKey: "eventLink")

                                                    do { try context.save() } catch {}



                                                }

                                            }

                                        }

                                    }

                                }

                            }

                        }

                    }

                }

                self.tableView.reloadData()

            } catch {}

        }

    }

    task.resume()

}

override func viewWillAppear(animated: Bool) {
    self.clearsSelectionOnViewWillAppear = self.splitViewController!.collapsed
    super.viewWillAppear(animated)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

// MARK: - Segues

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if segue.identifier == "showDetail" {

        if let indexPath = self.tableView.indexPathForSelectedRow {
            let object = self.fetchedResultsController.objectAtIndexPath(indexPath)
            let controller = (segue.destinationViewController as! UINavigationController).topViewController as! DetailViewController
            controller.detailItem = object
            controller.navigationItem.leftBarButtonItem = self.splitViewController?.displayModeButtonItem()
            controller.navigationItem.leftItemsSupplementBackButton = true
        }

    }

    if segue.identifier == "loginSegue" {

        checkForUser()

    }

}

// MARK: - Table View

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 1
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    let sectionInfo = self.fetchedResultsController.sections![section]
    return sectionInfo.numberOfObjects
    // Tried: return self.fetchedResultsController.fetchedObjects!.count
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath)

    self.configureCell(cell, atIndexPath: indexPath)

    return cell
}

func configureCell(cell: UITableViewCell, atIndexPath indexPath: NSIndexPath) {
    let object = self.fetchedResultsController.objectAtIndexPath(indexPath)
    cell.textLabel!.text = object.valueForKey("eventTitle")!.description

}

override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
    // Return false if you do not want the specified item to be editable.
    return false
}

var fetchedResultsController: NSFetchedResultsController {
    if _fetchedResultsController != nil {
        return _fetchedResultsController!
    }

    let fetchRequest = NSFetchRequest()
    // Edit the entity name as appropriate.
    let entity = NSEntityDescription.entityForName("ForumEvents", inManagedObjectContext: self.managedObjectContext!)
    fetchRequest.entity = entity

    // Set the batch size to a suitable number.
    fetchRequest.fetchBatchSize = 20

    // Edit the sort key as appropriate.
    let sortDescriptor = NSSortDescriptor(key: "eventTitle", ascending: false)

    fetchRequest.sortDescriptors = [sortDescriptor]

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: nil, cacheName: "Master")
    aFetchedResultsController.delegate = self
    _fetchedResultsController = aFetchedResultsController

    do {
        try _fetchedResultsController!.performFetch()
    } catch {
        // 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.
        //print("Unresolved error \(error), \(error.userInfo)")
        abort()
    }

    return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil

func controllerWillChangeContent(controller: NSFetchedResultsController) {
    self.tableView.beginUpdates()
}

}

以下是加载单元格结果的屏幕截图:

我已经尝试了所有方法，但不知道下一步该尝试什么!

预先感谢您的帮助。

Answer 1

确保 CoreData 正确。然后试试这个:

改变

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    let sectionInfo = self.fetchedResultsController.sections![section]
    return sectionInfo.numberOfObjects
}

进入

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return self.fetchResultController.fetchedObjects!.count
}