Unable to access NSManagedObject subclass properties (gives EXC_BAD_ACCESS)

Question

I am a noob in Core Data with Swift. I have one NSManagedObject class that looks like this:

 import Foundation import CoreData class Polls: NSManagedObject { @NSManaged var title: String @NSManaged var pollDescription: String } 

In a subclass of UITableViewController, I have a method for retrieving these objects, for example:

 func refreshPolls() { //do the query to populate the array let req = NSFetchRequest(entityName: "Polls") self.polls = self.managedObjectContext?.executeFetchRequest(req, error: nil) as! [Polls] println(polls.count) } 

Note that self.polls is defined as an array of polls.

Now, in cellForRowAtIndexPath: I just do this:

 override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell { var cell:UITableViewCell if indexPath.row==0 { cell = tableView.dequeueReusableCellWithIdentifier("EditPollCell") as! UITableViewCell } else { let poll:Polls = self.polls[indexPath.row-1] as Polls //println(poll.title) //fails with EXC_BAD_ACCESS cell = tableView.dequeueReusableCellWithIdentifier("PollCell") as! UITableViewCell //cell.textLabel?.text = (poll.valueForKey("title") as! String) } return cell 

Commented on println with EXC_BAD_ACCESS . No additional error information was provided, and adding “dynamic” to the attributes of the Polls class does not matter.

Why can't I access the properties of the Polls object? The use of the valueForKey method fails with the message "Unexpectedly found nil value when unpacking optional", even if the title property has a value.

Answer 1

I assume your Polls array is an NSManagedObject array. To check this, try replacing:

 //println(poll.title) //fails with EXC_BAD_ACCESS 

with

 println(poll.valueForKey("title")) 

If this helps, you can check this answer

CoreData: warning: unable to load class with name