CoreData delete single object

Question

I'd like to delete an entry in the entity Person at the attribute name which matches with the value Test.

For example I saved an entry into core data like this: object.setValue("Test", forKey: "markedCell"). Now I want to find out if the entry "Test" is saved in the attribute markedCell and which indexPath it has. I tried the following one:

var request:NSFetchRequest = NSFetchRequest(entityName: "Person") request.predicate = NSPredicate(format:"markedCell = %@", "Test") var results : [NSManagedObject] = context.executeFetchRequest(request, error: nil) as [NSManagedObject]

Now I know if the entry "Test" exists but don't know which indexPath it has (I can only delete an entry if I know which indexPath it has right?). Currently I want to delete the entry "Test" (don't wanna set it to "").

My CoreData model:

I want to delete "Test" from markedCell.

Does someone of you guys know how to do this in Swift ?

Creating a cell (cellForRowAtIndexPath):

//Get task
    let context = self.fetchedResultsController.managedObjectContext
    let object = self.fetchedResultsController.objectAtIndexPath(indexPath) as NSManagedObject
    var taskString:NSString?
    taskString = object.valueForKey("name") as? String
    cell.textLabel!.text = object.valueForKey("name") as? String

    println(object.valueForKey("name") as? String)

    //Set accessory type
    var request:NSFetchRequest = NSFetchRequest(entityName: "Person")
    request.predicate = NSPredicate(format:"markedCell = %@", taskString!)
    var results : [NSManagedObject] = context.executeFetchRequest(request, error: nil) as [NSManagedObject]
    if (results.count > 0) {
        //Element exists
        cell.accessoryType = UITableViewCellAccessoryType.None
        println("Cell isn't marked")
    }
    else {
        //Doesn't exist
        cell.accessoryType = UITableViewCellAccessoryType.DisclosureIndicator
        println("Cell is marked")
    }

Crash:

I hope this pic helps to understand my question better. The link of the image: https://www.dropbox.com/s/h5g4yeoedg0xjjv/Stackoverflow_Question.png?dl=0

Answer 1

I can only delete an entry if I know which indexPath it has right?

This is wrong. A Core Data object does not have an index path. (A fetched results controller manages Core Data objects for display in a table view and then you have index paths, but that is completely irrelevant here.)

Just fetch the object or the objects that you want to delete and delete them:

let request = NSFetchRequest(entityName: "Person")
request.predicate = NSPredicate(format:"markedCell = %@", "Test")
if let results = context.executeFetchRequest(request, error: nil) as? [NSManagedObject] {

    // Delete _all_ objects:
    for object in results {
        context.deleteObject(object)
    }

    // Or delete first object:
    if results.count > 0 {
        context.deleteObject(results[0])
    }

} else {
    // ... fetch failed, report error
}

Answer 2

For Swift 3:

       if let dataAppDelegatde = UIApplication.shared.delegate as? AppDelegate {


                let mngdCntxt = dataAppDelegatde.persistentContainer.viewContext

                let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "ItemCart")

                let predicate = NSPredicate(format: "itemId = %i", Int(currentItemID)!)
                print(currentItemID)

                fetchRequest.predicate = predicate
                do{
                    let result = try mngdCntxt.fetch(fetchRequest)

                    print(result.count)

                    if result.count > 0{
                        for object in result {
                            print(object)
                            mngdCntxt.delete(object as! NSManagedObject)
                        }
                    }
                }catch{

                }
            }