在后台Moc中删除对象然后在主Moc中刷新对象会导致NSFetchedResultsController更新崩溃

我遇到了NSObjectInaccessibleException我不明白的：

 *** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x8c40040 ''
*** First throw call stack:
(
    0   CoreFoundation                      0x01aa15e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x018248b6 objc_exception_throw + 44
    2   CoreData                            0x0025733b _PFFaultHandlerLookupRow + 2715
    3   CoreData                            0x00256897 -[NSFaultHandler fulfillFault:withContext:forIndex:] + 39
    4   CoreData                            0x00256473 _PF_FulfillDeferredFault + 259
    5   CoreData                            0x002562c6 _sharedIMPL_pvfk_core + 70
    6   CoreData                            0x0025acd5 -[NSManagedObject(_PFDynamicAccessorsAndPropertySupport) _genericValueForKey:withIndex:flags:] + 85
    7   CoreData                            0x00294781 _PF_Handler_Public_GetProperty + 161
    8   CoreData                            0x00294685 -[NSManagedObject valueForKey:] + 149
    9   Foundation                          0x01471a5a -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 409
    10  Foundation                          0x015079ba -[NSSortDescriptor compareObject:toObject:] + 166
    11  CoreData                            0x00366175 +[NSFetchedResultsController(PrivateMethods) _insertIndexForObject:inArray:lowIdx:highIdx:sortDescriptors:] + 309
    12  CoreData                            0x00360f61 -[NSFetchedResultsController(PrivateMethods) _postprocessInsertedObjects:] + 737
    13  CoreData                            0x00362c44 -[NSFetchedResultsController(PrivateMethods) _postprocessUpdatedObjects:] + 916
    14  CoreData                            0x00363578 -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 2152
    15  Foundation                          0x014f7bf9 __57-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke + 40
    16  CoreFoundation                      0x01afd524 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20
    17  CoreFoundation                      0x01a5500b _CFXNotificationPost + 2859
    18  Foundation                          0x01431951 -[NSNotificationCenter postNotificationName:object:userInfo:] + 98
    19  CoreData                            0x00268173 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 83
    20  CoreData                            0x0030778f -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 367
    21  CoreData                            0x00263e38 -[NSManagedObjectContext(_NSInternalChangeProcessing) _postRefreshedObjectsNotificationAndClearList] + 136
    22  CoreData                            0x002639e4 -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 3140
    23  CoreData                            0x00262d99 -[NSManagedObjectContext processPendingChanges] + 41
    24  CoreData                            0x00236fe1 _performRunLoopAction + 321
    25  CoreFoundation                      0x01a694ce __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
    26  CoreFoundation                      0x01a6941f __CFRunLoopDoObservers + 399
    27  CoreFoundation                      0x01a47344 __CFRunLoopRun + 1076
    28  CoreFoundation                      0x01a46ac3 CFRunLoopRunSpecific + 467
    29  CoreFoundation                      0x01a468db CFRunLoopRunInMode + 123
    30  GraphicsServices                    0x039029e2 GSEventRunModal + 192
    31  GraphicsServices                    0x03902809 GSEventRun + 104
    32  UIKit                               0x00592d3b UIApplicationMain + 1225
    33  RefreshDeletedTest                  0x00005d9d main + 141
    34  libdyld.dylib                       0x020df70d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type _NSCoreDataException

这是由特定的代码流引起的：

- (void)deleteObject:(NSManagedObject *)object {
    NSManagedObjectID *objID = object.objectID;
    NSManagedObjectContext *dataProcessingMoc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
    dataProcessingMoc.persistentStoreCoordinator = self.managedObjectContext.persistentStoreCoordinator;
    dataProcessingMoc.mergePolicy = NSMergeByPropertyObjectTrumpMergePolicy;
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataProcessingContextDidSave:) name:NSManagedObjectContextDidSaveNotification object:dataProcessingMoc];
    // If I use performBlockAndWait: instead of performBlock: the issue goes away.
    [dataProcessingMoc performBlock:^{
        NSManagedObject *objInDPMoc = [dataProcessingMoc objectWithID:objID];
        NSLog(@"Delete: %@", objInDPMoc);
        [dataProcessingMoc deleteObject:objInDPMoc]; // 1
        [object.managedObjectContext performBlockAndWait:^{
            [object.managedObjectContext refreshObject:object mergeChanges:NO]; // 2
        }];
        [dataProcessingMoc save:NULL]; // 3
    }];
}

- (void)dataProcessingContextDidSave:(NSNotification *)note {
    NSManagedObjectContext *moc = self.managedObjectContext;
    [moc performBlockAndWait:^{ // 3
        [moc mergeChangesFromContextDidSaveNotification:note];
        NSError *error;
        if ([moc hasChanges] && ![moc save:&error]) {
            NSLog(@"Unresolved error %@", error);
            abort();
        }
    }];
}

注意：代码看起来很怪异，没有太大意义。这是我将实际代码减少到最少的错误再现代码的结果。

删除背景Moc中的对象。

刷新相同的对象以使它成为主要的故障。

保存背景Moc，并使用将其更改合并到主Moc NSManagedObjectContextDidSaveNotification。

例外发生在真正的合并之前，即在主Moc的调用下performBlockAndWait:。

这是崩溃时后台Moc的线程堆栈：

#0  0x02210fb6 in semaphore_wait_trap ()
#1  0x01e3ccde in _dispatch_thread_semaphore_wait ()
#2  0x01e3a516 in _dispatch_barrier_sync_f_slow ()
#3  0x01e3a413 in dispatch_barrier_sync_f ()
#4  0x0028bf1f in -[NSManagedObjectContext performBlockAndWait:] ()
#5  0x000037b5 in -[MasterViewController dataProcessingContextDidSave:] at /Users/an0/dev/Projects/iOS/Study/RefreshDeletedTest/RefreshDeletedTest/MasterViewController.m:84
#6  0x014f7bf9 in __57-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke ()
#7  0x01afd524 in __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ ()
#8  0x01a5500b in _CFXNotificationPost ()
#9  0x01431951 in -[NSNotificationCenter postNotificationName:object:userInfo:] ()
#10 0x0027bb2c in -[NSManagedObjectContext(_NSInternalAdditions) _didSaveChanges] ()
#11 0x0026720f in -[NSManagedObjectContext save:] ()
#12 0x0000345a in __37-[MasterViewController cleanObjects:]_block_invoke at /Users/an0/dev/Projects/iOS/Study/RefreshDeletedTest/RefreshDeletedTest/MasterViewController.m:78
#13 0x003047c3 in developerSubmittedBlockToNSManagedObjectContextPerform_privateasync ()
#14 0x01e4d4b0 in _dispatch_client_callout ()
#15 0x01e3b07f in _dispatch_queue_drain ()
#16 0x01e3ae7a in _dispatch_queue_invoke ()
#17 0x01e3be1f in _dispatch_root_queue_drain ()
#18 0x01e3c137 in _dispatch_worker_thread2 ()
#19 0x021d9dab in _pthread_wqthread ()

为什么会这样崩溃？我的代码是真的错误还是错误Core Data？

我无法理解的另一个奇怪的事情是，在此类崩溃之后，该应用程序将无法再启动，因为它将在启动时崩溃：

2014-01-05 12:31:34.151 RefreshDeletedTest[3546:70b] *** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0xa88d060 ''
*** First throw call stack:
(
    0   CoreFoundation                      0x01aa05e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x018238b6 objc_exception_throw + 44
    2   CoreData                            0x0025633b _PFFaultHandlerLookupRow + 2715
    3   CoreData                            0x00255897 -[NSFaultHandler fulfillFault:withContext:forIndex:] + 39
    4   CoreData                            0x00255473 _PF_FulfillDeferredFault + 259
    5   CoreData                            0x002552c6 _sharedIMPL_pvfk_core + 70
    6   CoreData                            0x00259cd5 -[NSManagedObject(_PFDynamicAccessorsAndPropertySupport) _genericValueForKey:withIndex:flags:] + 85
    7   CoreData                            0x00293781 _PF_Handler_Public_GetProperty + 161
    8   CoreData                            0x00293685 -[NSManagedObject valueForKey:] + 149
    9   Foundation                          0x014a8f0a -[NSArray(NSKeyValueCoding) valueForKey:] + 456
    10  Foundation                          0x01470a5a -[NSObject(NSKeyValueCoding) valueForKeyPath:] + 409
    11  Foundation                          0x0149b99d -[NSArray(NSKeyValueCoding) valueForKeyPath:] + 580
    12  CoreData                            0x0035b7e9 -[NSFetchedResultsController performFetch:] + 697
    13  RefreshDeletedTest                  0x00003910 -[MasterViewController fetchedResultsController] + 800
    14  RefreshDeletedTest                  0x0000307e -[MasterViewController numberOfSectionsInTableView:] + 78
    15  UIKit                               0x007e5b94 -[UITableViewRowData(UITableViewRowDataPrivate) _updateNumSections] + 102
    16  UIKit                               0x007e6993 -[UITableViewRowData invalidateAllSections] + 69
    17  UIKit                               0x0065d237 -[UITableView _updateRowData] + 194
    18  UIKit                               0x0065d170 -[UITableView _ensureRowDataIsLoaded] + 45
    19  UIKit                               0x006704b3 -[UITableView numberOfSections] + 35
    20  UIKit                               0x0084d3d3 -[UITableViewController viewWillAppear:] + 103
    21  UIKit                               0x006a8bfa -[UIViewController _setViewAppearState:isAnimating:] + 419
    22  UIKit                               0x006a9108 -[UIViewController __viewWillAppear:] + 114
    23  UIKit                               0x006cb3f5 -[UINavigationController _startTransition:fromViewController:toViewController:] + 800
    24  UIKit                               0x006cc09c -[UINavigationController _startDeferredTransitionIfNeeded:] + 645
    25  UIKit                               0x006cccb9 -[UINavigationController __viewWillLayoutSubviews] + 57
    26  UIKit                               0x00806181 -[UILayoutContainerView layoutSubviews] + 213
    27  UIKit                               0x0e35656f -[UILayoutContainerViewAccessibility(SafeCategory) layoutSubviews] + 50
    28  UIKit                               0x005fc267 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 355
    29  libobjc.A.dylib                     0x0183581f -[NSObject performSelector:withObject:] + 70
    30  QuartzCore                          0x045802ea -[CALayer layoutSublayers] + 148
    31  QuartzCore                          0x045740d4 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 380
    32  QuartzCore                          0x04580235 -[CALayer layoutIfNeeded] + 160
    33  UIKit                               0x006b7613 -[UIViewController window:setupWithInterfaceOrientation:] + 304
    34  UIKit                               0x005d6177 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:isRotating:] + 5212
    35  UIKit                               0x005d4d16 -[UIWindow _setRotatableClient:toOrientation:updateStatusBar:duration:force:] + 82
    36  UIKit                               0x005d4be8 -[UIWindow _setRotatableViewOrientation:updateStatusBar:duration:force:] + 117
    37  UIKit                               0x005d4c70 -[UIWindow _setRotatableViewOrientation:duration:force:] + 67
    38  UIKit                               0x005d3d0a __57-[UIWindow _updateToInterfaceOrientation:duration:force:]_block_invoke + 120
    39  UIKit                               0x005d3c6c -[UIWindow _updateToInterfaceOrientation:duration:force:] + 400
    40  UIKit                               0x005d49c3 -[UIWindow setAutorotates:forceUpdateInterfaceOrientation:] + 870
    41  UIKit                               0x005d7fb6 -[UIWindow setDelegate:] + 449
    42  UIKit                               0x006a9737 -[UIViewController _tryBecomeRootViewControllerInWindow:] + 180
    43  UIKit                               0x005cdc1c -[UIWindow addRootViewControllerViewIfPossible] + 609
    44  UIKit                               0x005cdd97 -[UIWindow _setHidden:forced:] + 312
    45  UIKit                               0x005ce02d -[UIWindow _orderFrontWithoutMakingKey] + 49
    46  UIKit                               0x0e332c66 -[UIWindowAccessibility(SafeCategory) _orderFrontWithoutMakingKey] + 77
    47  UIKit                               0x005d889a -[UIWindow makeKeyAndVisible] + 65
    48  UIKit                               0x0058bcd0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 1851
    49  UIKit                               0x005903a8 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
    50  UIKit                               0x005a487c -[UIApplication handleEvent:withNewEvent:] + 3447
    51  UIKit                               0x005a4de9 -[UIApplication sendEvent:] + 85
    52  UIKit                               0x00592025 _UIApplicationHandleEvent + 736
    53  GraphicsServices                    0x039032f6 _PurpleEventCallback + 776
    54  GraphicsServices                    0x03902e01 PurpleEventCallback + 46
    55  CoreFoundation                      0x01a1bd65 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
    56  CoreFoundation                      0x01a1ba9b __CFRunLoopDoSource1 + 523
    57  CoreFoundation                      0x01a4677c __CFRunLoopRun + 2156
    58  CoreFoundation                      0x01a45ac3 CFRunLoopRunSpecific + 467
    59  CoreFoundation                      0x01a458db CFRunLoopRunInMode + 123
    60  UIKit                               0x0058fadd -[UIApplication _run] + 840
    61  UIKit                               0x00591d3b UIApplicationMain + 1225
    62  RefreshDeletedTest                  0x0000508d main + 141
    63  libdyld.dylib                       0x020de70d start + 1
)
libc++abi.dylib: terminating with uncaught exception of type _NSCoreDataException

这是您可以运行以亲自查看问题的示例项目：http : //d.pr/f/y3VQ