每隔一段时间，我在应用程序中收到以下错误消息。这是在我的应用程序通过RestKit与CoreData集成收到Web服务响应后发生的：
CoreData: error: Serious application error. Exception was caught during Core Data change processing. This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification. no object at index 3 in section at index 0 with userInfo (null)
2014-07-28 12:48:26.348 Identify[43074:60b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'no object at index 3 in section at index 0'
*** First throw call stack:
(
0 CoreFoundation 0x0270e1e4 __exceptionPreprocess + 180
1 libobjc.A.dylib 0x0248d8e5 objc_exception_throw + 44
2 CoreData 0x006d7dbe -[NSFetchedResultsController objectAtIndexPath:] + 398
3 Identify 0x0002d03e -[WTSRecordListViewController configureCell:atIndexPath:] + 190
4 Identify 0x0002c5f6 -[WTSRecordListViewController controller:didChangeObject:atIndexPath:forChangeType:newIndexPath:] + 646
5 CoreData 0x006df296 -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 5238
6 Foundation 0x02160049 __57-[NSNotificationCenter addObserver:selector:name:object:]_block_invoke + 40
7 CoreFoundation 0x02769f04 __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20
8 CoreFoundation 0x026c1efb _CFXNotificationPost + 2859
9 Foundation 0x02099e41 -[NSNotificationCenter postNotificationName:object:userInfo:] + 98
10 CoreData 0x005e1a13 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 83
11 CoreData 0x00680faf -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 367
12 CoreData 0x005dceb8 -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 2152
13 CoreData 0x005e02fc -[NSManagedObjectContext save:] + 140
14 Identify 0x000d1ffd __61-[NSManagedObjectContext(RKAdditions) saveToPersistentStore:]_block_invoke + 125
15 CoreData 0x0060584f developerSubmittedBlockToNSManagedObjectContextPerform + 95
16 CoreData 0x0060578c -[NSManagedObjectContext performBlockAndWait:] + 140
17 Identify 0x000d1b83 -[NSManagedObjectContext(RKAdditions) saveToPersistentStore:] + 739
18 Identify 0x00048d28 __80-[WTSObjectManager getRecordsForUser:forGroup:startIndex:limit:success:failure:]_block_invoke_2 + 2456
19 Identify 0x0014f551 __66-[RKObjectRequestOperation setCompletionBlockWithSuccess:failure:]_block_invoke244 + 97
20 libdispatch.dylib 0x02f747b8 _dispatch_call_block_and_release + 15
21 libdispatch.dylib 0x02f894d0 _dispatch_client_callout + 14
22 libdispatch.dylib 0x02f77726 _dispatch_main_queue_callback_4CF + 340
23 CoreFoundation 0x0277343e __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 14
24 CoreFoundation 0x026b45cb __CFRunLoopRun + 1963
25 CoreFoundation 0x026b39d3 CFRunLoopRunSpecific + 467
26 CoreFoundation 0x026b37eb CFRunLoopRunInMode + 123
27 GraphicsServices 0x0367c5ee GSEventRunModal + 192
28 GraphicsServices 0x0367c42b GSEventRun + 104
29 UIKit 0x0114df9b UIApplicationMain + 1225
30 Identify 0x0000279d main + 141
31 libdyld.dylib 0x031be701 start + 1
进入此状态后，如果不移除应用并将其重新添加到设备上，则无法修复此问题。我正在使用苹果为核心数据获取结果控制器定义的库存样板代码：
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
NSLog(@"begin updates");
[self.tableView beginUpdates];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
switch(type) {
case NSFetchedResultsChangeInsert:
NSLog(@"inserting section");
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
NSLog(@"deleting section");
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
NSLog(@"inserting row");
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
NSLog(@"deleting row");
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
NSLog(@"update row");
[self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
NSLog(@"move row");
[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
NSLog(@"end updates");
[self.tableView endUpdates];
}
configureCell方法看起来像这样，当我从fetchedResultsController获取记录时失败：
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
//if a nil cell was passed into this method, just return
if (!cell) {
return;
}
WTSRecordCell *recordCell = (WTSRecordCell *)cell;
WTSRecord *record = [self.fetchedResultsController objectAtIndexPath:indexPath];
...
}
以下代码是我创建fetchedResultsController的地方。在我的应用程序中，我创建了两个单独的WTSRecordListViewController实例，其中一个带有获取请求，返回＆＃39;记录＆＃39;由用户和其他人返回＆＃39;记录＆＃39;小组。
- (NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController == nil) {
WTSUserInfo *userInfo = [WTSConfiguration sharedConfig].orgConfig.userInfo;
NSFetchRequest *fetchRequest = nil;
if (self.type == RecordListTypeUser) {
fetchRequest = [[WTSObjectManager sharedManager] fetchRequestForRecordsByUser:userInfo.username];
} else if (self.type == RecordListTypeGroup) {
fetchRequest = [[WTSObjectManager sharedManager] fetchRequestForRecordsByGroup:userInfo.groupId];
}
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"createDt" ascending:NO];
NSArray *sortDescriptors = @[sortDescriptor];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:@"sectionName" cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
// Replace this implementation with code to handle the error appropriately.
// abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
DDLogWarn(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
return _fetchedResultsController;
}
我不确定我在这里做错了什么，如果这是Apple代码中的某种错误。就像我之前说过的那样，这只会偶尔发生一次（可能是当后端核心数据处于某种非常特定的状态时，因为我似乎永远不会在它发生之后重新创建它）。
修改
经过一些额外的搜索后，我发现导致问题的代码。在我正在进行的Web服务调用的RestKit中的success块中，我遍历了一些设置某些值的数据库对象。当我完成迭代值时，我调用[context saveToPersistentStore];该调用是导致获取结果控制器方法被触发的原因。如果我发表saveToPersistentStore来电，我就不会得到例外。
RestKit中的success块在主线程上执行。另外，根据我的打印输出，该块在controllerWillChangeContent:和controllerDidChangeContent:方法之外执行。
编辑2： 以下代码是我通过RestKit进行Web服务调用的地方。在其中，我遍历在映射数组中返回的对象，设置如何获取记录以便以后进行孤立清除。我还对未从获取请求返回的记录执行获取请求并清除标记（也用于孤立清除）。
否则我的RestKit成功阻止在哪里检查以确保删除映射请求中返回的对象，或者在修改它们之前删除从获取请求返回的对象。这是我需要做的事情吗？
[self.rkObjectManager getObjectsAtPathForRouteNamed:kWTSRecordsRouteName object:nil parameters:params success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSArray *records = [mappingResult array];
//we put the record ids we get back in the request in a set
NSMutableSet *recordIds = [NSMutableSet new];
//set in the record how this was fetched
NSManagedObjectContext *context = nil;
for (WTSRecord *record in records) {
[recordIds addObject:record.recordId];
if (!context) {
context = record.managedObjectContext;
}
if (groupId) {
record.fetchedViaGroup = [NSNumber numberWithBool:YES];
} else {
record.fetchedViaUser = [NSNumber numberWithBool:YES];
}
}
//if the startIndex is 0, the user is refreshing. We clear the 'fetchedVia*' field for any records that DID NOT come back in this request
if (startIndex == 0) {
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"WTSRecord"];
if (groupId) {
request.predicate = [NSPredicate predicateWithFormat:@"recordId != nil AND fetchedViaGroup == 1 AND pendingDelete == 0"];
} else {
request.predicate = [NSPredicate predicateWithFormat:@"recordId != nil AND fetchedViaUser == 1 AND pendingDelete == 0", user];
}
NSArray *records = [context executeFetchRequest:request error:nil];
for (WTSRecord *record in records) {
if (![recordIds containsObject:record.recordId]) {
if (groupId) {
record.fetchedViaGroup = [NSNumber numberWithBool:NO];
} else {
record.fetchedViaUser = [NSNumber numberWithBool:NO];
}
}
}
}
//save the changes to the persistent store
[context saveToPersistentStore:nil];
success(records);
dispatch_semaphore_signal(sem);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
failure(error);
dispatch_semaphore_signal(sem);
}];
编辑3 我在上面的代码段中找到了导致问题的代码：
//set in the record how this was fetched
NSManagedObjectContext *context = nil;
for (WTSRecord *record in records) {
[recordIds addObject:record.recordId];
if (!context) {
context = record.managedObjectContext;
}
// if (groupId) {
// record.fetchedViaGroup = [NSNumber numberWithBool:YES];
// } else {
// record.fetchedViaUser = [NSNumber numberWithBool:YES];
// }
}
通过以下注释掉的行，我可以毫无问题地拨打saveToPersistentStore。我在这做错了什么？修改mappingResult中返回的对象并将更改保存到本地数据存储的可接受方法是什么？
答案 0 :(得分：2)
我不知道你如何设置视图控制器的所有详细信息，我的最佳答案是，当我有这个问题时，这个问题经常发生在我身上。
一个。将表视图插入视图控制器
B中。将数据保存在同一个View Controller中。
无论我的情况如何，如果您要在具有表视图的视图中保存数据，您需要删除代码中的以下方法：
- (void) controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath
和
-(void) controller:(NSFetchedResultsController *)controller didChangeSection:(id<NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
发生的错误是因为获取的结果突然发生了表视图尚无法识别的更改，即。 “no object at index 3 in section at index 0”。
如果您希望表格响应更改，您需要添加refresh方法并在保存数据后调用它（听起来很明显，但Stack Exchange有一部分不明白的人那个）即。 [self refresh];所以在你的-(IBAction *) save: (id) sender方法中（如果你使用它来保存，则为void方法），从那里调用它。
希望这有助于将来的任何人。