Good morning, I've developed an application where we download a JSON of objects and we store those information on a CoreData table. We've also created a Collection view used to show those information through a NSFetchedResultsController. Can someone helps me to understand the reason why I get this issue? Thanks indeed Fatal Exception: NSInvalidArgumentException 0 CoreFoundation 0x83f20 __exceptionPreprocess 1 libobjc.A.dylib 0x16018 objc_exception_throw 2 CoreFoundation 0x1b6250 _NSArrayRaiseInsertNilException 3 CoreFoundation 0x16f5c -[__NSCFArray objectAtIndex:] 4 CoreData 0x13af14 -[_PFMutableProxyArray subarrayWithRange:] 5 CoreData 0xc4948 -[_NSDefaultSectionInfo objects] 6 CoreData 0x9c3fc -[NSFetchedResultsController _conditionallyDispatchSnapshotToDelegate:updatesInfo:] 7 CoreData 0x6d4ec __82-[NSFetchedResultsController(PrivateMethods) _core_managedObjectContextDidChange:]_block_invoke 8 CoreData 0x270dc developerSubmittedBlockToNSManagedObjectContextPerform 9 CoreData 0x9d0ec -[NSManagedObjectContext performBlockAndWait:] 10 CoreData 0x9c6e8 -[NSFetchedResultsController _core_managedObjectContextDidChange:] 11 CoreFoundation 0x5178c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ 12 CoreFoundation 0x516a8 ___CFXRegistrationPost_block_invoke 13 CoreFoundation 0x515f0 _CFXRegistrationPost 14 CoreFoundation 0x4fbb8 _CFXNotificationPost 15 Foundation 0x31574 -[NSNotificationCenter postNotificationName:object:userInfo:] 16 CoreData 0x6a548 -[NSManagedObjectContext _createAndPostChangeNotification:deletions:updates:refreshes:deferrals:wasMerge:] 17 CoreData 0x69d10 -[NSManagedObjectContext _postRefreshedObjectsNotificationAndClearList] 18 CoreData 0x68a4c -[NSManagedObjectContext _processRecentChanges:] 19 CoreData 0x91494 -[NSManagedObjectContext _coreMergeChangesFromDidSaveDictionary:usingObjectIDs:withClientQueryGeneration:] 20 CoreData 0x90334 -[NSManagedObjectContext mergeChangesFromContextDidSaveNotification:] 21 CoreData 0x270dc developerSubmittedBlockToNSManagedObjectContextPerform 22 libdispatch.dylib 0x3dd4 _dispatch_client_callout 23 libdispatch.dylib 0x125a4 _dispatch_main_queue_drain 24 libdispatch.dylib 0x121b8 _dispatch_main_queue_callback_4CF 25 CoreFoundation 0x56710 __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ 26 CoreFoundation 0x53914 __CFRunLoopRun 27 CoreFoundation 0x52cd8 CFRunLoopRunSpecific 28 GraphicsServices 0x11a8 GSEventRunModal 29 UIKitCore 0x40a90c -[UIApplication _run] 30 UIKitCore 0x4be9d0 UIApplicationMain 31 Rainbow 0x80c0 main + 15 (main.swift:15) 32 ??? 0x1b3419e4c (Mancante)

Good morning, I've developed an application in order to show the information stored into a CoraData Table on a CollectionView through a NSFetchedResultsController. Several times I got this issue, is there anyone who can help me to understand the reason why this happens? Thanks indeed. Fatal Exception: NSInvalidArgumentException 0 CoreFoundation 0x83f20 __exceptionPreprocess 1 libobjc.A.dylib 0x16018 objc_exception_throw 2 CoreFoundation 0x1b6250 _NSArrayRaiseInsertNilException 3 CoreFoundation 0x16f5c -[__NSCFArray objectAtIndex:] 4 CoreData 0x13af14 -[_PFMutableProxyArray subarrayWithRange:] 5 CoreData 0xc4948 -[_NSDefaultSectionInfo objects] 6 CoreData 0x9c3fc -[NSFetchedResultsController _conditionallyDispatchSnapshotToDelegate:updatesInfo:] 7 CoreData 0x6d4ec __82-[NSFetchedResultsController(PrivateMethods) _core_managedObjectContextDidChange:]_block_invoke 8 CoreData 0x270dc developerSubmittedBlockToNSManagedObjectContextPerform 9 CoreData 0x9d0ec -[NSManagedObjectContext performBlockAndWait:] 10 CoreData 0x9c6e8 -[NSFetchedResultsController _core_managedObjectContextDidChange:] 11 CoreFoundation 0x5178c CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER 12 CoreFoundation 0x516a8 ___CFXRegistrationPost_block_invoke 13 CoreFoundation 0x515f0 _CFXRegistrationPost 14 CoreFoundation 0x4fbb8 _CFXNotificationPost 15 Foundation 0x31574 -[NSNotificationCenter postNotificationName:object:userInfo:] 16 CoreData 0x6a548 -[NSManagedObjectContext _createAndPostChangeNotification:deletions:updates:refreshes:deferrals:wasMerge:] 17 CoreData 0x69d10 -[NSManagedObjectContext _postRefreshedObjectsNotificationAndClearList] 18 CoreData 0x68a4c -[NSManagedObjectContext _processRecentChanges:] 19 CoreData 0x91494 -[NSManagedObjectContext _coreMergeChangesFromDidSaveDictionary:usingObjectIDs:withClientQueryGeneration:] 20 CoreData 0x90334 -[NSManagedObjectContext mergeChangesFromContextDidSaveNotification:] 21 CoreData 0x270dc developerSubmittedBlockToNSManagedObjectContextPerform 22 libdispatch.dylib 0x3dd4 _dispatch_client_callout 23 libdispatch.dylib 0x125a4 _dispatch_main_queue_drain 24 libdispatch.dylib 0x121b8 _dispatch_main_queue_callback_4CF 25 CoreFoundation 0x56710 CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE 26 CoreFoundation 0x53914 __CFRunLoopRun 27 CoreFoundation 0x52cd8 CFRunLoopRunSpecific 28 GraphicsServices 0x11a8 GSEventRunModal 29 UIKitCore 0x40a90c -[UIApplication _run] 30 UIKitCore 0x4be9d0 UIApplicationMain 31 Cloud 0x80c0 main + 15 (main.swift:15) 32 ??? 0x1b3419e4c (Mancante)