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", inManagedObjectContext: moc),
            insertIntoManagedObjectContext: moc)

That seems like it should work. Nothing tricky.

My very similar Person entity with a to-many relationship can be inserted (and saved) correctly with Swift (as evidenced in the passing testSwiftToMany test) . The more-complicated Objective-C version also succeeds with the same data model (the passing testObjcToOneAndToMany test).

Here's the entire exception:

file:///%3Cunknown%3E: test failure: -[SwiftCoreDataRelationshipReproTests testSwiftToOne()] failed: failed: caught "NSInvalidArgumentException", "An NSManagedObject of class 'NSManagedObject' must have a valid NSEntityDescription."
(
    0   CoreFoundation                      0x00007fff8dd6525c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff84ce5e75 objc_exception_throw + 43
    2   CoreData                            0x00007fff8765dd16 -[NSManagedObject initWithEntity:insertIntoManagedObjectContext:] + 550
    3   SwiftCoreDataRelationshipReproTests 0x0000000100394d4a _TTOFCSo15NSManagedObjectcfMS_FT6entityGSQCSo19NSEntityDescription_30insertIntoManagedObjectContextGSQCSo22NSManagedObjectContext__S_ + 42
    4   SwiftCoreDataRelationshipReproTests 0x00000001003946bd _TFCSo15NSManagedObjectCfMS_FT6entityGSQCSo19NSEntityDescription_30insertIntoManagedObjectContextGSQCSo22NSManagedObjectContext__S_ + 93
    5   SwiftCoreDataRelationshipReproTests 0x0000000100393450 _TFC35SwiftCoreDataRelationshipReproTests35SwiftCoreDataRelationshipReproTests14testSwiftToOnefS0_FT_T_ + 816
    6   SwiftCoreDataRelationshipReproTests 0x00000001003934c2 _TToFC35SwiftCoreDataRelationshipReproTests35SwiftCoreDataRelationshipReproTests14testSwiftToOnefS0_FT_T_ + 34
    7   CoreFoundation                      0x00007fff8dc50a5c __invoking___ + 140
    8   CoreFoundation                      0x00007fff8dc508c4 -[NSInvocation invoke] + 308
    9   XCTest                              0x00000001003b023a -[XCTestCase invokeTest] + 253
    10  XCTest                              0x00000001003b03ac -[XCTestCase performTest:] + 142
    11  XCTest                              0x00000001003b8ad0 -[XCTest run] + 257
    12  XCTest                              0x00000001003af68b -[XCTestSuite performTest:] + 379
    13  XCTest                              0x00000001003b8ad0 -[XCTest run] + 257
    14  XCTest                              0x00000001003af68b -[XCTestSuite performTest:] + 379
    15  XCTest                              0x00000001003b8ad0 -[XCTest run] + 257
    16  XCTest                              0x00000001003af68b -[XCTestSuite performTest:] + 379
    17  XCTest                              0x00000001003b8ad0 -[XCTest run] + 257
    18  XCTest                              0x00000001003acc8f __25-[XCTestDriver _runSuite]_block_invoke + 56
    19  XCTest                              0x00000001003b773d -[XCTestObservationCenter _observeTestExecutionForBlock:] + 162
    20  XCTest                              0x00000001003acbc8 -[XCTestDriver _runSuite] + 269
    21  XCTest                              0x00000001003ad34a -[XCTestDriver _checkForTestManager] + 551
    22  XCTest                              0x00000001003bb879 +[XCTestProbe runTests:] + 175
    23  Foundation                          0x00007fff8e0aacb7 __NSFireDelayedPerform + 333
    24  CoreFoundation                      0x00007fff8dccc494 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
    25  CoreFoundation                      0x00007fff8dccbfcf __CFRunLoopDoTimer + 1151
    26  CoreFoundation                      0x00007fff8dd3d5aa __CFRunLoopDoTimers + 298
    27  CoreFoundation                      0x00007fff8dc87755 __CFRunLoopRun + 1525
    28  CoreFoundation                      0x00007fff8dc86f25 CFRunLoopRunSpecific + 309
    29  HIToolbox                           0x00007fff8e566a0d RunCurrentEventLoopInMode + 226
    30  HIToolbox                           0x00007fff8e566685 ReceiveNextEventCommon + 173
    31  HIToolbox                           0x00007fff8e5665bc _BlockUntilNextEventMatchingListInModeWithFilter + 65
    32  AppKit                              0x00007fff8538e26e _DPSNextEvent + 1434
    33  AppKit                              0x00007fff8538d8bb -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 122
    34  AppKit                              0x00007fff853819bc -[NSApplication run] + 553
    35  AppKit                              0x00007fff8536c7a3 NSApplicationMain + 940
    36  SwiftCoreDataRelationshipRepro      0x000000010000ad55 top_level_code + 37
    37  SwiftCoreDataRelationshipRepro      0x000000010000ad8a main + 42
    38  libdyld.dylib                       0x00007fff861115fd start + 1
)

Answer 1

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.