Pre Populate Core Data with a method - swift

Question

I created an extension for my Core Data subclass, here I implemented a method to pre populate the table, first I check if here is anything in the table, and I insert some values, but I get an error when I do a fetch:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'executeFetchRequest:error: <null> is not a valid NSFetchRequest.'
import Foundation
import CoreData
extension SimulationParams {
public static func feedSimulationParams(context: NSManagedObjectContext) {
let fetchRequest : NSFetchRequest<NSFetchRequestResult>
if #available(iOS 10.0, *) {
fetchRequest = SimulationParams.fetchRequest()
} else {
fetchRequest = NSFetchRequest(entityName: "SimulationParams")
}
let idDescriptor: NSSortDescriptor = NSSortDescriptor(key: "id", ascending: false)
fetchRequest.sortDescriptors = [idDescriptor]
fetchRequest.fetchLimit = 1
var newId = 0;
do {
let results = try context.fetch(fetchRequest)
if(results.count == 0){
self.setValue(getId(fetchRequest: fetchRequest, context: context), forKeyPath: "id")
self.setValue(1.5, forKeyPath: "bankFeePercentage")
self.setValue(1, forKeyPath: "consoMaxMonthly")
self.setValue(12, forKeyPath: "consoMinMonthly")
self.setValue(3.5, forKeyPath: "consoRatePercentage")
self.setValue(4, forKeyPath: "fileFeePercentage")
self.setValue(1, forKeyPath: "immoMaxMonthly")
self.setValue(25, forKeyPath: "immoMinMonthly")
self.setValue(2.05, forKeyPath: "immoRatePercentage")
self.setValue(3, forKeyPath: "prepaymentPenaltyPercentage")
self.setValue(1, forKeyPath: "notaryGridId")
do {
try context.save()
} catch let error as NSError {
print ("Error first demande insertion \(error)")
}
}
} catch {
let fetchError = error as NSError
print(fetchError)
}
}
}

Answer 1

Solution:
Warning, you have to delete the module in the Data Model Inspector and set it to global namespace.
You have to do this on your code:
let fetchRequest : NSFetchRequest<NSFetchRequestResult>
if #available(iOS 10.0, *) {
fetchRequest = Params.fetchRequest()
} else {
fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Params")
}
//let predicate = NSPredicate(format: "key=%#", key)
//fetchRequest.predicate = predicate
do {
let results = try context.fetch(fetchRequest)
if(results.count != 0){
let params = NSEntityDescription.insertNewObject(forEntityName: "Params", into: context) as! Params
params.setValue(value, forKey: "value")
do {
try context.save()
} catch let error as NSError {
print ("Error first demande insertion \(error)")
}
} else if (results.count == 0) {
let params = NSEntityDescription.insertNewObject(forEntityName: "Params", into: context) as! Params
params.key = key
params.value = value
context.insert(params)
}
} catch {
let fetchError = error as NSError
print(fetchError)
}