从Coredata Swift中删除数据

Question

在我的tableViewController中,我有以下内容.我试图删除一个项目工作.

var myData: Array<AnyObject> = []

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cellID: NSString = "Cell"
    var Cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
    var data: NSManagedObject = myData[indexPath.row] as NSManagedObject
    Cell.textLabel?.text = data.valueForKeyPath("Name") as? String

    return Cell
}

然后尝试删除我有.

override func tableView(tableView: (UITableView!), commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    if editingStyle == .Delete {
        let cellID: NSString = "Cell"
        var Cell: UITableViewCell = tableView.dequeueReusableCellWithIdentifier(cellID) as UITableViewCell
        var data: NSManagedObject = myData[indexPath.row] as NSManagedObject
        data.delete(0)

        // 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
    }
}

Answer 1

在swift和coredata中执行删除数据时更新我的​​编码问题.这个代码我最终得到了它.

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
        switch editingStyle {
        case .Delete:
            // remove the deleted item from the model
            let appDel:AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
            let context:NSManagedObjectContext = appDel.managedObjectContext!
            context.deleteObject(myData[indexPath.row] as NSManagedObject)
            myData.removeAtIndex(indexPath.row)
            context.save(nil)

           //tableView.reloadData()
            // remove the deleted item from the `UITableView`
            self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
        default:
            return

        }
}

编辑上面的Swift 2.2和Xcode 7.3.1

override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
    switch editingStyle {
    case .Delete:
        // remove the deleted item from the model
        let appDel:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
        let context:NSManagedObjectContext = appDel.managedObjectContext
        context.deleteObject(myData[indexPath.row] )
        myData.removeAtIndex(indexPath.row)
        do {
            try context.save()
        } catch _ {
        }

        // remove the deleted item from the `UITableView`
        self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
    default:
        return
    }
}

还需要纠正这两行代码.

    var myData: Array<AnyObject> = []
let managedObjectContext = (UIApplication.sharedApplication().delegate as AppDelegate).managedObjectContext

Answer 2

Swift 3.0

下面是删除项目和重新加载数据的代码.

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {

     let noteEntity = "Note" //Entity Name

     let managedContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext

     let note = notes[indexPath.row]

     if editingStyle == .delete {
        managedContext.delete(note)

        do {
            try managedContext.save()
        } catch let error as NSError {
            print("Error While Deleting Note: \(error.userInfo)")
        }

     }

    //Code to Fetch New Data From The DB and Reload Table.
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: noteEntity)

    do {
        notes = try managedContext.fetch(fetchRequest) as! [Note]
    } catch let error as NSError {
        print("Error While Fetching Data From DB: \(error.userInfo)")
    }
    noteTableView.reloadData()
}

Answer 3

要完成zisoft的答案:

删除对象后需要保存上下文.

所以正确的方法是:

// get your app managemenent context

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

// remove your object

context.del(data)

// save your changes 
context.save(nil)

注意首先检查是否有任何删除规则(如果您有任何相关对象)