[NSTaggedPointerString managedObjectContext]: unrecognized selector - core-data

Question

I am trying to save additions to a data model using Swift 3. I am getting errors, -[NSTaggedPointerString managedObjectContext]: unrecognized selector sent to instance 0xa00e8808201a0cc8. I have checked the data model and all items referred to in the save are consistent with the data model. My save code is:
let entity = NSEntityDescription.entity(forEntityName: "TransectPlants", in: coreDataStack.context)!
let plantObservation = NSManagedObject(entity: entity, insertInto: coreDataStack.context)
plantObservation.setValue(selectedFamilyName, forKey: "plantFamily")
plantObservation.setValue(selectedSpeciesName, forKey: "plantSpecies")
plantObservation.setValue(transectNameString, forKey: "transectTitle")
do {
try coreDataStack.context.save()
} catch let error as NSError {
print("Could not save. \(error), \(error.userInfo)")
}
The data model is :
[][1
I have used this as my coreDataStack:
import Foundation
import CoreData
class CoreDataStack {
let modelName = "TransectWalkaboutPro"
lazy var context: NSManagedObjectContext = {
var managedObjectContext = NSManagedObjectContext(
concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = self.psc
return managedObjectContext
}()
fileprivate lazy var psc: NSPersistentStoreCoordinator = {
let coordinator = NSPersistentStoreCoordinator(
managedObjectModel: self.managedObjectModel)
let url = self.applicationDocumentsDirectory
.appendingPathComponent("TransectWalkaboutPro.sqlite")
do {
let options =
[NSMigratePersistentStoresAutomaticallyOption : true, NSInferMappingModelAutomaticallyOption : true ]
try coordinator.addPersistentStore(
ofType: NSSQLiteStoreType, configurationName: nil, at: url,
options: options)
} catch {
print("Error adding persistent store.")
}
return coordinator
}()
fileprivate lazy var managedObjectModel: NSManagedObjectModel = {
let modelURL = Bundle.main
.url(forResource: self.modelName,
withExtension: "momd")!
return NSManagedObjectModel(contentsOf: modelURL)!
}()
fileprivate lazy var applicationDocumentsDirectory: URL = {
let urls = FileManager.default.urls(
for: .documentDirectory, in: .userDomainMask)
return urls[urls.count-1]
}()
func saveContext () {
if context.hasChanges {
do {
try context.save()
} catch let error as NSError {
print("Error: \(error.localizedDescription)")
abort()
}
}
}
}
I cannot see any inconsistencies that would cause the unrecognised selector, what may I be missing?

Answer 1

The line
plantObservation.setValue(transectNameString, forKey: "transectTitle")
causes the error. According to your model the value for key transectTitle must be a managed object instance of Transect rather than a string.