我遇到了一个 NSObjectInaccessibleException 我无法理解。
*** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x8c40040 <x-coredata://85B02C1C-1FFC-4CBF-B7AC-EEA259115427/Event/p6>''
*** 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
这是由一个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： 这段代码看起来很奇怪，而且没有什么意义。这是我把真实的代码缩减到最小的错误产生代码的结果。
NSManagedObjectContextDidSaveNotification.异常发生在真正的合并之前，在主moc调用的 performBlockAndWait:.
这是崩溃时后台moc的线程栈。
#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？是我的代码真的出错了还是我的代码出了bug？Core Data?
还有一个奇怪的事情，我不能理解的是，在这样的崩溃后，应用程序不能再启动，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 <x-coredata://93009ECF-EC6E-4B12-BC40-997C4BF3B8DF/Event/p11>''
*** 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
这是一个示例项目，你可以自己运行看看问题。http:/d.prfy3VQ
在多线程环境中，没有办法避免这个问题。
只要你有2个不同的上下文在同一层次上（无论是父子架构还是直接连接到存储），你可能会遇到这样的情况：一个上下文删除了一个对象（并向存储提交了更改），而另一个上下文试图在更改被合并之前访问这个对象。这种情况也可能发生在父上下文向存储提交变更，而它的子上下文试图访问他所持有的被删除的项目的故障时。一般来说，在每一个地方，在提交之前，变化并没有在上下文之间自动传播，都有机会得到这个异常。
如果你能将你的上下文流水线化(store-context1-context2-...)，并且只从链中的最后一个上下文删除，你就可以避免这个问题。
你可以设计一些算法来延迟你的删除操作，使它们只有在没有其他上下文使用特定项目时才会被提交，但这涉及到你的很多记账工作。
你可以通过获取完整的(无故障)对象，或者你将处理的整个子图(使用FRC时无法做到)，并在这些对象上进行操作，从而减少上下文之间的冲突。
这在 2015年WWDC 220核心数据有什么新变化？ 随着iOS 9的发布和 shouldDeleteInaccessibleFaults 身上 NSManagedObjectContext.
目前，shouldDeleteInaccessibleFaults默认为是.如果遇到故障，我们会将故障标记为删除，任何缺失的属性将为null，nil或零.这允许你的应用程序继续使用这个对象，并将其视为已删除的对象.你不再会崩溃，但你将能够仅仅继续下去，并向用户展示他们期望看到的东西。