iOS swift core data persistence problem: Lost and thrashing - ios

Question

I may have done a really stupid thing.
In writing an upgrade for my (first) shipped app, I changed the schema of my Core Data model, adding another entity (Issuer) and creating a to-many relationship with the existing entity (Coin). I thought the lightweight migration had successfully taken care of the change:
Before:
After:
Here's the Core Data stack, created automatically when I created the project:
lazy var persistentContainer: NSPersistentContainer = {
let container = NSPersistentContainer(name: "Coin_Portfolio")
let description = NSPersistentStoreDescription()
description.shouldInferMappingModelAutomatically = true
description.shouldMigrateStoreAutomatically = true
container.persistentStoreDescriptions = [description]
container.loadPersistentStores(completionHandler: { (storeDescription, error) in
if let error = error as NSError? {
fatalError("Unresolved error \(error), \(error.userInfo)")
}
})
return container
}()
In testing on my iPhone, I found that I could create Coins, like this:
func createNewCoin(){
guard let appDelegate =
UIApplication.shared.delegate as? AppDelegate else {
return
}
let context = appDelegate.persistentContainer.viewContext
newCoin = NSEntityDescription.insertNewObject(forEntityName: "Coin", into: context) as! Coin
if currentOwner.name == nil {
print("In NewCoin, createNewCoin, currentOwner is nil")
}else{
print("In NewCoin, createNewCoin, currentOwner is named \(String(describing: currentOwner.name))")
}
// Problem with contexts could be here! Compare DB for this app to test bed
newCoin.denomination = nil
newCoin.grade = nil
newCoin.itemIdentifier = ""
newCoin.mintMark = nil
currentOwner.addToCoins(newCoin)
saveIt()
}
func saveIt(){
guard let appDelegate =
UIApplication.shared.delegate as? AppDelegate else {
return
}
appDelegate.saveContext()
}
And retrieve it like this:
let context = appDelegate.persistentContainer.viewContext
let ownerFetchRequest :
NSFetchRequest<Issuer> = Issuer.fetchRequest()
do {
try ownerFRC?.performFetch()
owners = try context.fetch(ownerFetchRequest)
} catch {
fatalError("Failed to initialize FetchedResultsController: \(error)")
}
for owner in owners{
if owner.name == currentOwner.name{
currentOwnerCoinsByDenom = ((owner.coins?.allObjects as! [Coin]).sorted(by: { $0.denomination! < $1.denomination! }))
currentOwnerCoinsByYear = ((currentOwnerCoinsByDenom as! [Coin]).sorted(by: { $0.denomination! < $1.denomination! }))
print ("currentOwnerCoinsByDenom.count == \(currentOwnerCoinsByDenom)")
print(currentOwnerCoinsByDenom.count)
print ("currentOwnerCoinsByYear.count == \(currentOwnerCoinsByYear)")
print(currentOwnerCoinsByYear.count)
}
}
}
Fine, as long as I don't quit the app and relaunch it.
Upon relaunch, my fetch attempts return no Coins, even though I know that there had been some 80+ records stored in Core Data before the schema change.
I then started what I thought was a rational approach to solving the problem. See iOS data saved in Core Data doesn't survive launch. The answers received, unfortunately, didn't solve the problem.
Accordingly, I panicked, knowing my users wouldn't take kindly to losing their own records.
Here's where I may have run off the rails: I created a duplicate project in order to try to resolve the issue without screwing up my original. But I continue to experience the same problem.
I have examined the dataBase(s) using DB Browser for SQLite, but am very confused as to which DB I'm downloading -- is it the original, or the one created by the duplicate project? They both have the same name, but one of them has the original records, the other only one record.
Any ideas how I can save myself? I'm flummoxed and desperate! Will gladly supply any needed info or code.
All help deeply appreciated!