Question

我是我的应用程序中的核心数据的新手我正在使用coredata。我只是将数据存储在我的核心数据中。我的实体名称是“FEED”，我有一个名为“title”，“id”，“link”，“desc”的行，所以现在我想基于“id”删除特定行。那怎么能这样呢？

这是我的代码，

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell : MessageMusicCell = tableView.dequeueReusableCellWithIdentifier("MessageMusicCell") as! MessageMusicCell

    cell.pinButton.tag = indexPath.row
    cell.pinButton.addTarget(self, action: #selector(MessageViewController.buttonDeletePressed(_:)), forControlEvents: UIControlEvents.TouchUpInside)
    cell.selectionStyle = .None



        person = people[indexPath.row]
        cell.lbl_title_msg_music.text = person!.valueForKey("title") as? String
        cell.img_message_music.image = UIImage(named: "PlaceHolder")
        cell.desc_msg_music.text = person!.valueForKey("desc") as? String


    return cell
}

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

        print(people.count)
        return people.count


}

func buttonDeletePressed(sender:UIButton) {


}
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {

    let cell : MessageMusicCell = tableView.dequeueReusableCellWithIdentifier("MessageMusicCell") as! MessageMusicCell


}

所以我该怎么做？

Answer 1

尝试这样，

func buttonDeletePressed(sender:UIButton) {

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

        let index = sender.tag

        context.deleteObject(people[index] as NSManagedObject)
        people.removeAtIndex(index)

        let _ : NSError! = nil
        do {
            try context.save()
            self.tableView.reloadData()
        } catch {
            print("error : \(error)")
        }
}

希望这会对你有所帮助。

Answer 2

    $(document).ready(function(){
        $('#inpImage').change(function(){
            readURL(this, drawImage);
        });
        function drawImage(img)  {
            var canvas = document.getElementById("myCanvas");
            var cContext = canvas.getContext('2d');

            var size = scaleSize(400, 600, img.width, img.height);
            var width = size[0];
            var height = size[1];

            canvas.setAttribute('width', width);
            canvas.setAttribute('height', height);

            cContext.beginPath();
            cContext.rect(0, 0, width, height);
            cContext.fillStyle = "red";
            cContext.fill();

            cContext.drawImage(img, 0, 0, width, height);
        };
    });
    function readURL(input, drawImage) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();
            reader.onload = function (e) {
                var img = new Image();
                img.onload = function(){
                    drawImage(img);
                };
                img.src = e.target.result;
            }
            reader.readAsDataURL(input.files[0]);
        }
    }

    function scaleSize(maxW, maxH, currW, currH) {
        var ratio = currH / currW;
        if (currW >= maxW && ratio <= 1) {
            currW = maxW;
            currH = currW * ratio;
        } else if (currH >= maxH) {
            currH = maxH;
            currW = currH / ratio;
        }
        return [currW, currH];
    }

现在你可以调用这个函数并传递你想要删除的id

func deleteFeed(id:String)
{
    let appDelegate =
        UIApplication.sharedApplication().delegate as? AppDelegate
    let managedContext = appDelegate?.managedObjectContext
    let fetchRequest = NSFetchRequest(entityName:"FEED")
    fetchRequest.predicate = NSPredicate(format: "id = %@", "\(id)")
    do
    {
        let fetchedResults =  try managedContext!.executeFetchRequest(fetchRequest) as? [NSManagedObject]

        for entity in fetchedResults! {

            managedContext?.deleteObject(entity)
        }
    }
    catch _ {
        print("Could not delete")

    }
}

Answer 3

您可以删除

等数据

  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)

这是从commitEditingStyle完成的，所以这里使用了indexPath.row。如果要从其他位置删除数据，可以传递您的ID。如果要从tableview中删除数据，则应实现commitEditingStyle并删除上述数据。

希望这会有所帮助：）

Answer 4

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(people[indexPath.row] )
    people.removeAtIndex(indexPath.row)
    do {
        try context.save()
    } catch _ {
    }

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

希望这可能有所帮助！

如何删除coredata（实体）ios swift中的行

4 个答案: