首先我要说的是，我对使用 Xcode/Swift 制作应用程序非常陌生。我从来没有真正用 Obj-C 做过任何事情，所以 Swift 确实是我第一次接触 iOS 编码。

我的问题是我试图在删除核心数据记录后删除表格单元格。我似乎能够很好地删除核心数据，但每次尝试删除单元格行时都会出现相同的错误。

我得到的错误如下:

2016-03-10 08:49:56.484 EZ List[31764:3225607] * Assertion failure in -[UITableView _endCellAnimationsWithContext:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit_Sim/UIKit-3512.30.14/UITableView.m:1720 2016-03-10 08:49:56.487 EZ List[31764:3225607] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (2) must be equal to the number of rows contained in that section before the update (2), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).' [... And so on]

我用来删除的代码是这样的:

override func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {

    let delete = UITableViewRowAction(style: .Destructive, title: "Delete") { (action, indexPath) in
        // delete item at indexPath
        let request = self.fetchRequest()
        var fetchResults = [AnyObject]()

        do {
            fetchResults = try self.moc.executeFetchRequest(request)
        } catch {
            fatalError("Fetching Data to Delete Failed")
        }

        self.moc.deleteObject(fetchResults[indexPath.row] as! NSManagedObject)

        fetchResults.removeAtIndex(indexPath.row)

        do {
            try self.moc.save()
        } catch {
            fatalError("Failed to Save after Delete")
        }

        self.lists.removeAtIndex(indexPath.row)
        self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)

    }

    let edit = UITableViewRowAction(style: .Normal, title: "Edit") { (action, indexPath) in
        // edit item at indexPath

    }

    edit.backgroundColor = UIColor.init(red: 84/255, green: 200/255, blue: 214/255, alpha: 1)

    return [delete, edit]

}

经过大量测试后，我确认问题出在

self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)

但是我不明白为什么它认为sections中的行是无效的。任何帮助将不胜感激。到目前为止，我所有的搜索都得出了 Obj-C 答案或似乎无法解决我的问题的快速答案。

编辑: 为 numberOfRowsInSection 添加代码

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of rows
    if let sections = frc.sections {
        let currentSection = sections[section]
        return currentSection.numberOfObjects
    }

    return 0
}

编辑2: 这是我的 ViewController 的完整代码 **请记住，我一直在尝试一些不同的方法来使其正常工作，因此其中有一些注释掉的东西。

import UIKit
import CoreData

class ListTableViewController: UITableViewController, NSFetchedResultsControllerDelegate {

let moc = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
var frc: NSFetchedResultsController = NSFetchedResultsController()
var lists : [Lists] = []

/*
var listNames: [String] = ["Any List", "Other List"]
var listItemCount: [Int] = [5, 6]
var listIcons: [UIImage] = [UIImage(named: "Generic List")!, UIImage(named: "Generic List")!]
*/

override func viewWillAppear(animated: Bool) {

    let imageView = UIImageView(image: UIImage(named: "TableBackground"))
    imageView.contentMode = .ScaleAspectFill
    self.tableView.backgroundView = imageView
    self.tableView.tableFooterView = UIView(frame: CGRectZero)
    do {
        self.lists = try moc.executeFetchRequest(fetchRequest()) as! [Lists]
    } catch {
        fatalError("Failed setting lists array to fetch request")
    }
    self.tableView.reloadData()

}

override func viewDidLoad() {
    super.viewDidLoad()

    checkAnyList()

    frc = getFCR()
    frc.delegate = self

    do {
        try frc.performFetch()
    } catch {
        fatalError("Failed to perform inital fetch")
    }

    self.tableView.reloadData()

    // Uncomment the following line to preserve selection between presentations
    //self.clearsSelectionOnViewWillAppear = true

    // Uncomment the following line to display an Edit button in the navigation bar for this view controller.
    // self.navigationItem.rightBarButtonItem = self.editButtonItem()
}

override func viewDidAppear(animated: Bool) {

    checkAnyList()

    frc = getFCR()
    frc.delegate = self

    do {
        try frc.performFetch()
    } catch {
        fatalError("Failed to perform inital fetch")
    }

    self.tableView.reloadData()

}

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

// MARK: - Table view data source

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    // #warning Incomplete implementation, return the number of sections
    if let sections = frc.sections {
        return sections.count
    }

    return 0
}

override func tableView(tableView: UITableView, willDisplayCell cell: UITableViewCell, forRowAtIndexPath indexPath: NSIndexPath) {

    cell.backgroundColor = UIColor.clearColor()

}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    // #warning Incomplete implementation, return the number of rows
    if let sections = frc.sections {
        let currentSection = sections[section]
        return currentSection.numberOfObjects
    }

    return 0
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    let listCellReturn = tableView.dequeueReusableCellWithIdentifier("listCell", forIndexPath: indexPath) as! ListTableViewCell

    //let list = frc.objectAtIndexPath(indexPath) as! Lists
    let list = self.lists[indexPath.row]

    listCellReturn.separatorInset = UIEdgeInsets(top: 0, left: 78, bottom: 0, right: 0)

    listCellReturn.listNameLabel.text = list.name
    listCellReturn.listIconImage.image = UIImage(data: (list.image)!)

    /*
    listCellReturn.listNameLabel.text = listNames[indexPath.row]
    listCellReturn.itemCountLabel.text = "Items: \(listItemCount[indexPath.row])"
    listCellReturn.listIconImage.image = listIcons[indexPath.row]
    */

    return listCellReturn
}

override func tableView(tableView: UITableView, editActionsForRowAtIndexPath indexPath: NSIndexPath) -> [UITableViewRowAction]? {

    let delete = UITableViewRowAction(style: .Destructive, title: "Delete") { (action, indexPath) in
        // delete item at indexPath
        let request = self.fetchRequest()
        var fetchResults = [AnyObject]()

        do {
            fetchResults = try self.moc.executeFetchRequest(request)
        } catch {
            fatalError("Fetching Data to Delete Failed")
        }

        self.moc.deleteObject(fetchResults[indexPath.row] as! NSManagedObject)

        fetchResults.removeAtIndex(indexPath.row)

        do {
            try self.moc.save()
        } catch {
            fatalError("Failed to Save after Delete")
        }

        self.lists.removeAtIndex(indexPath.row)
        self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)

    }

    let edit = UITableViewRowAction(style: .Normal, title: "Edit") { (action, indexPath) in
        // edit item at indexPath

    }

    edit.backgroundColor = UIColor.init(red: 84/255, green: 200/255, blue: 214/255, alpha: 1)

    return [delete, edit]

}

func fetchRequest() -> NSFetchRequest {

    let fetchRequest = NSFetchRequest(entityName: "Lists")
    let sortDescriptor = NSSortDescriptor(key: "name", ascending: true)
    fetchRequest.sortDescriptors = [sortDescriptor]

    return fetchRequest

}

func getFCR() -> NSFetchedResultsController {

    frc = NSFetchedResultsController(fetchRequest: fetchRequest(), managedObjectContext: moc, sectionNameKeyPath: nil, cacheName: nil)

    return frc

}

func checkAnyList() {

    var exists: Bool = false

    let fetchReq = NSFetchRequest(entityName: "Lists")
    let pred = NSPredicate(format: "%K == %@", "name", "Any List")
    fetchReq.predicate = pred

    do {
        let check = try moc.executeFetchRequest(fetchReq)
        for rec in check {
            if let name = rec.valueForKey("name") {
                if (name as! String == "Any List") {
                    exists = true
                }
            }
        }

        if (exists == false) {
            let entityDesc = NSEntityDescription.entityForName("Lists", inManagedObjectContext: moc)
            let list = Lists(entity: entityDesc!, insertIntoManagedObjectContext: moc)

            list.name = "Any List"
            list.image = UIImagePNGRepresentation(UIImage(named: "Any List")!)

            do {
                try moc.save()
            } catch {
                fatalError("New list save failed")
            }
        }
    } catch {
        fatalError("Error checking for Any List")
    }

        //let check = try moc.executeFetchRequest(fetchReq)
        //for rec in check {

        //} catch {

}

/*
// Override to support conditional editing of the table view.
override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
    // Return false if you do not want the specified item to be editable.
    return true
}
*/

/*
// Override to support editing the table view.
override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    if editingStyle == .Delete {
        // Delete the row from the data source
        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
    } else if editingStyle == .Insert {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }    
}
*/

/*
// Override to support rearranging the table view.
override func tableView(tableView: UITableView, moveRowAtIndexPath fromIndexPath: NSIndexPath, toIndexPath: NSIndexPath) {

}
*/

/*
// Override to support conditional rearranging of the table view.
override func tableView(tableView: UITableView, canMoveRowAtIndexPath indexPath: NSIndexPath) -> Bool {
    // Return false if you do not want the item to be re-orderable.
    return true
}
*/

// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}

最佳答案

你需要调用...

self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: UITableViewRowAnimation.Automatic)

...当您的数据源已更改时。当您调用上述方法时，它会询问您的 tableView 的委托(delegate)该部分中有多少行，并且该方法仍返回 2。一旦已知该方法返回 1，您必须调用上述方法。

编辑:获得更多信息后更新。

查看NSFetchedResultsControllerDelegate 的引用资料(Reference)。它详细说明了您应该如何处理与 UITableView 相关的数据更改。基本上从您的编辑方法中删除 deleteRowsAtIndexPaths，而是在适当的委托(delegate)方法中执行 tableView 更新。这些方面的内容应该对您有所帮助(摘自上述引用资料):

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath {

    UITableView *tableView = self.tableView;

    switch(type) {

        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                   withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                   withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath]
                atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                   withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                   withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

您可能不需要处理每种情况。 NSFetchedResultsController 引用资料也很有帮助(Reference)。

关于ios - 删除核心数据中的记录后无法删除索引处的表行，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/35922613/