Array Index Out of Bounds issue (NSRangeException) in -[NSManagedObjectContext save:] - ios

Question

My iOS application just crashed with a NSRangeException on -[NSManagedObjectContext save:]. Nothing else helpful anywhere to be found. How am I supposed to fix this? I don't get any memory address or anything that I can work with...
2015-04-22 14:16:38.078 heavenhelp[33559:1734247] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 6 beyond bounds [0 .. 5]'
*** First throw call stack:
(
0 CoreFoundation 0x0167f746 __exceptionPreprocess + 182
1 libobjc.A.dylib 0x00f40a97 objc_exception_throw + 44
2 CoreFoundation 0x01553b73 -[__NSArrayM objectAtIndex:] + 243
3 CoreData 0x00859cf3 -[NSSQLCore recordToManyChangesForObject:inRow:usingTimestamp:inserted:] + 2531
4 CoreData 0x00856a0b -[NSSQLCore _populateRow:fromObject:timestamp:inserted:] + 2923
5 CoreData 0x00776e24 -[NSSQLCore prepareForSave:] + 1764
6 CoreData 0x00775e3d -[NSSQLCore saveChanges:] + 461
7 CoreData 0x0073f15e -[NSSQLCore executeRequest:withContext:error:] + 638
8 CoreData 0x0083ee75 __65-[NSPersistentStoreCoordinator executeRequest:withContext:error:]_block_invoke + 5349
9 CoreData 0x008492ff gutsOfBlockToNSPersistentStoreCoordinatorPerform + 191
10 libdispatch.dylib 0x035f4bef _dispatch_client_callout + 14
11 libdispatch.dylib 0x035d7b0d _dispatch_barrier_sync_f_invoke + 144
12 libdispatch.dylib 0x035d723f dispatch_barrier_sync_f + 105
13 CoreData 0x008383f7 _perform + 183
14 CoreData 0x0073ec8b -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 459
15 CoreData 0x0076ee09 -[NSManagedObjectContext save:] + 1529
16 heavenhelp 0x000b6834 _TF10heavenhelp11saveContextFT_T_ + 324
17 heavenhelp 0x0015368d _TFC10heavenhelp26ConversationViewController17viewWillDisappearfS0_FSbT_ + 701
18 heavenhelp 0x001536ef _TToFC10heavenhelp26ConversationViewController17viewWillDisappearfS0_FSbT_ + 63
19 UIKit 0x020a4292 -[UIViewController _setViewAppearState:isAnimating:] + 706
20 UIKit 0x020a4904 -[UIViewController __viewWillDisappear:] + 106
21 UIKit 0x020bcd1d -[UIViewController(UIContainerViewControllerProtectedMethods) beginAppearanceTransition:animated:] + 200
22 UIKit 0x020cafec -[UINavigationController _startCustomTransition:] + 1028
23 UIKit 0x020d8e00 -[UINavigationController _startDeferredTransitionIfNeeded:] + 712
24 UIKit 0x020d9a51 -[UINavigationController __viewWillLayoutSubviews] + 57
25 UIKit 0x02253750 -[UILayoutContainerView layoutSubviews] + 213
26 UIKit 0x01fce57a -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 668
27 libobjc.A.dylib 0x00f56771 -[NSObject performSelector:withObject:] + 70
28 QuartzCore 0x01d5ee47 -[CALayer layoutSublayers] + 144
29 QuartzCore 0x01d52925 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 403
30 QuartzCore 0x01d5277a _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 26
31 QuartzCore 0x01caec52 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 284
32 QuartzCore 0x01cb00e5 _ZN2CA11Transaction6commitEv + 487
33 QuartzCore 0x01cb07fc _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 92
34 CoreFoundation 0x015a086e __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 30
35 CoreFoundation 0x015a07b0 __CFRunLoopDoObservers + 400
36 CoreFoundation 0x015961ea __CFRunLoopRun + 1226
37 CoreFoundation 0x01595a5b CFRunLoopRunSpecific + 443
38 CoreFoundation 0x0159588b CFRunLoopRunInMode + 123
39 GraphicsServices 0x046cc2c9 GSEventRunModal + 192
40 GraphicsServices 0x046cc106 GSEventRun + 104
41 UIKit 0x01f3b106 UIApplicationMain + 1526
42 heavenhelp 0x000a5c94 main + 180
43 libdyld.dylib 0x0361fac9 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
This is the code I used to make my save: thread-safe:
static var onceToken: dispatch_once_t = 0
static var singleton: CoreDataHelper!
static var sharedInstance: CoreDataHelper {
get {
dispatch_once(&onceToken, {
self.singleton = CoreDataHelper()
})
return singleton
}
}
My xcdatamodeld (the relevant part):
Edits: I have edited the code to reflect my changes to make my NSManagedObjectContext thread-safe. Everything I do now, I do on one instance of my CoreDataHelper that I initialise as above. I have found I can trigger a crash by going into one conversation, adding a message, going into another conversation and adding a message there. I have added my xcdatamodeld.

Answer 1

I had apparently set my one-to-many relationship between conversations and messages to "ordered". This was not correct... I had already changed my NSManagedObject's class to use NSMutableSet instead of NSMutableOrderedSet.
Apparently this results in an NSRangeException in the save method...

Answer 2

you said you have made your save-method thread save. can you please show some code?
usually i'm doing something like this:
// create object with concurrency where you need it
[[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
// wrapper for saving
- (BOOL)saveContext
{
__block BOOL success = NO;
NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
if (managedObjectContext != nil)
{
[managedObjectContext performBlockAndWait:^{
if([managedObjectContext hasChanges])
{
NSError *error = nil;
success = [managedObjectContext save:&error];
if (success == NO)
{
NSLog(#"Unresolved error %#", error.localizedDescription);
}
}
}];
}
return success;
}

Answer 3

Somewhere in AppDelegate you are creating NSArray,
By adding Exception Breakpoint you can check the line which causes error.
method to add Exception Breakpoint is on the following links.
http://blog.manbolo.com/2012/01/23/xcode-tips-1-break-on-exceptions
https://developer.apple.com/library/ios/recipes/xcode_help-breakpoint_navigator/articles/adding_an_exception_breakpoint.html