Can't load Core Data in to-many attribute - ios

Question

I have been unable to add and read core data attributes in a one-to-many
relationship. After reading many SO, Apple Docs and other articles I still have
not accomplished this. To make a simple test, I created a standard Master Detail
App with Core Data. This works with no issues for the main entity.
The core data relationship is as shown below.
Here is the code to place some test data into the store. Note that I am
attempting to add the to-many data as a Set for each InvItem and have made the
keywordList attribute Transformable. I thought this was the best approach, but
obviously that is not working here.
func seedInvItems(num : Int) {
for index in 1...num {
let newManagedObject = NSEntityDescription.insertNewObjectForEntityForName("InvItem", inManagedObjectContext: kAppDelegate.managedObjectContext) as! InvItem
newManagedObject.name = "myName\(index)"
newManagedObject.category1 = "myCategory1x\(index)"
newManagedObject.compartment = "myCompartment\(index)"
newManagedObject.entryDate = NSDate()
//and for the one-to-many relationship
var myStoreKeywordSet = Set<String>()
myStoreKeywordSet = ["one","two","three"]
// do an insert just for grins
myStoreKeywordSet.insert("four")
let newManagedObject2 = NSEntityDescription.insertNewObjectForEntityForName("InvItemKeyword", inManagedObjectContext: kAppDelegate.managedObjectContext) as! InvItemKeyword
newManagedObject2.keywordList = myStoreKeywordSet
}//for in
kAppDelegate.saveContext()
let fetchRequestTest = NSFetchRequest(entityName: "InvItem")
let sorter : NSSortDescriptor = NSSortDescriptor(key: "name", ascending: true)
fetchRequestTest.sortDescriptors = [sorter]
var resultsTest : [InvItem]?
do {
resultsTest = try kAppDelegate.managedObjectContext.executeFetchRequest(fetchRequestTest) as? [InvItem]
for object in resultsTest! {
let myRetrieveKeywordSet = object.invitemkeywords
print(myRetrieveKeywordSet)
}//for in
} catch let error as NSError {
//what happens on failure
print("And the executeFetchRequest error is \(error.localizedDescription)")
}//do catch
}//seedInvItems
For completeness, I did create the NSManagedObject subclasses for the Core
Data Entities.
When running the app, the master detail for InvItem behaves as expected but I
get no storage of the to-many items.
Here is the console log (for one InvItem):
Optional(Relationship 'invitemkeywords' fault on managed object (0x7f985a62bb70) (entity: InvItem; id: 0xd000000000700000 ; data: {
category1 = myCategory1x3;
compartment = myCompartment3;
entryDate = "2016-02-09 02:10:21 +0000";
invitemkeywords = "";
name = myName3;
}))
Looking at the database, there is no data for the keywordList.
Any help would be appreciated. Xcode 7.2.1 IOS 9.2

Answer 1

You need to set the relationship from newManagedObject to newManagedObject2. In fact, because the relationship is one-many, it is easier to set the to-one relationship:
newManagedObject2.invitem = newManagedObject
and let CoreData handle the inverse, to-many relationship.
As to the keyWordList not being populated, I wonder whether your SQL browser is unable to decode CoreData's NSSet? I also wonder whether you need to have keywordList as an NSSet? The relationship from InvItem is already to-many, so your model implies that each InvItem can have many InvItemKeywords, each of which holds many keywords in its keywordList attribute: is that what you intended?