Inserting an NSManagedObject in Swift with a To-One Relationship

Question

I'm having trouble simply inserting an NSManagedObject with a to-one relationship when using Swift on Xcode 6b3. I put my repro on GitHub but the failing code (in `SwiftCoreDataRelationshipReproTests.swift`'s `testSwiftToOne` unit test method) boils down to this: ``` let momURL : NSURL = NSBundle.mainBundle().URLForResource("SwiftCoreDataRelationshipRepro", withExtension: "momd") let mom : NSManagedObjectModel = NSManagedObjectModel(contentsOfURL: momURL) let psc : NSPersistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: mom); let ps : NSPersistentStore = psc.addPersistentStoreWithType( NSInMemoryStoreType, configuration: nil, URL: nil, options: nil, error: nil) let moc : NSManagedObjectContext = NSManagedObjectContext() moc.persistentStoreCoordinator = psc // This throws an NSInvalidArgumentException: "An NSManagedObject of class 'NSManagedObject' must have a valid NSEntityDescription." NSManagedObject( entity: NSEntityDescription.entityForName("Pet", inManaged…

Accepted Answer

So I couldn't solve the problem, but I think I narrowed it down to a bug in the framework or Swift. Using `entityForName` is equivalent to getting the entity directly out of the managedObjectModel so I tried to do it that way:

```
let entities = moc.persistentStoreCoordinator.managedObjectModel.entitiesByName;
let keys = Array(entities.keys)
let petVar : String = keys[1] as String
let isEqual1 = (petVar == "Pet") // true
let isEqual2 = (petVar.hashValue == "Pet".hashValue) // true

let result1 = entities["Pet"] // nil
let result2 = entities[petVar] // non-nil
let result3 = entities.bridgeToObjectiveC().objectForKey("Pet".bridgeToObjectiveC()) // nil
let result4 = entities.bridgeToObjectiveC().objectForKey(petVar.bridgeToObjectiveC()) // non-nil

// Doesn't Pass
XCTAssertNotNil(NSEntityDescription.entityForName("Pet", inManagedObjectContext: moc));

// Passes
XCTAssertNotNil(NSEntityDescription.entityForName(petVar, inManagedObjectContext: moc));
```

It works with the key pulled out of the dictionary but not a string that is equivalent to the key (even the hash values are the same).

I think that this pretty definitely shows that there is a bug either in the framework or in Swift itself. I am running Xcode (6b3) and 10.9.4

I think it is time for a bug report.

Inserting an NSManagedObject in Swift with a To-One Relationship

Solution

Problem