Open Radar

 
Core Data works from the playground when there are no entities that use specific managed object subclasses, but when you set a managedObjectClassName in any of the entities, it crashes with: "Execution was interrupted, reason: EXC_BAD_ACCESS". This happens both when you define the NSManagedObject subclass in the playground itself or when you are referencing one that is contained in a module that was loaded in the playground.

To Reproduce:

Paste the following code into the Playground (either iOS or OSX) and observe the crash. Note that commenting out the "entity.managedObjectClassName = className" line lets it succeed.

import Foundation
import CoreData

@objc class SomeEntity : NSManagedObject {
    @NSManaged var stringField: String
}

let mom = NSManagedObjectModel()

let entity = NSEntityDescription()
entity.name = "SomeEntity"

let className = NSStringFromClass(SomeEntity.self)
entity.managedObjectClassName = className

let attr = NSAttributeDescription()
attr.name = "stringField"
attr.attributeType = NSAttributeType.StringAttributeType
entity.properties = [attr]

mom.entities = [entity]

let ctx = NSManagedObjectContext()
let ob = NSManagedObject(entity: entity, insertIntoManagedObjectContext: ctx)
ob.setValue("This is some string", forKey: "stringField")
ob.valueForKey("stringField")