在表视图中删除核心数据对象

Question

I am new to Swift and I am following a tutorial about making a gesture-driven app.

As in the tutorial, a table view is populated from array objects.

There is a function to remove an item from the table view when the user drags the cell to the left.

func toDoItemDeleted(toDoItem: ToDoItem) {
  let index = (toDoItems as NSArray).indexOfObject(toDoItem)
  if index == NSNotFound { return }

  // could removeAtIndex in the loop but keep it here for when indexOfObject works
  toDoItems.removeAtIndex(index)

  // use the UITableView to animate the removal of this row
  tableView.beginUpdates()
  let indexPathForRow = NSIndexPath(forRow: index, inSection: 0)
  tableView.deleteRowsAtIndexPaths([indexPathForRow], withRowAnimation: .Fade)
  tableView.endUpdates()    
}

In the tutorial the array is named toDoItems , and there is also a NSObject class named ToDoItem .

In my implentation, I am using Core Data instead of an array to populate the table view. I have create a NSObject named Tasks instead of the NSObject from the tutorial.

How should I change the function to remove the Core Data object instead of the array object?

Thank you.

Answer 1

Your problem is that you are removing the NSManagedObject from the array, but not from the managed object context. To remove it from Core Data, you should remove it from your managed object context like so:

managedObjectContext?.deleteObject(toDoItem)
managedObjectContext?.save(nil)

However, if you are using Core Data to populate a UITableView, I would advise using NSFetchedResultsController. A complete implementation can be found here .

Answer 2

1. Delete Item from Core Data
2. Delete Item from your NSObject Array
3. Remove That Row from UITableView

Write Below Code In commitEditingStyle Method

if editingStyle == .Delete {

       // Step : 1
        let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate

        let manageContext = appDelegate.managedObjectContext!
        // I have Store Item in Data which is type of NSManagedObject
        // This will remove item from coredata
        manageContext.deleteObject(Data[indexPath.row])

        var err:NSError?

        if !manageContext.save(&err)
        {
           println("Data couldn't delete")
        }
        // Step : 2 Delete the row from the data source

        self.Data.removeAtIndex(indexPath.row)

        // Step 3:
        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
    }