On Feb 2, 2015, at 17:36:22, Roland King <r...@rols.org> wrote:
>
> get the NSManagedObjectContext the document creates for you with [ super
> managedObjectContext ], get the store coordinator with [ managedObjectContext
> persistentStoreCoordinator ], create your own MOCs on that store, hold on to
> the MOC you have just created, ignore the one super created (or perhaps you
> can nil it, not sure) and then return it.
That sounds interesting. I've tried it, and it causes my managedObjectContext
override to be called twice during document creation. The 2nd call is caused by
my managedObjectContext override calling [super managedObjectContext], and
super tries to set up the undo manager for its managedObjectContext. I don't
know if this is harmless or OK.
So since no exceptions are thrown during the creating of my own MOCs, I go
ahead and add objects to a temp private MOC whose parent is my
managedObjectContext. That works and my table view is populated after it
completes. But when I try to save at the end of my concurrent object-adding
block, it throws:
CoreData: error: Illegal attempt to save to a file that was never opened. "This
NSPersistentStoreCoordinator has no persistent stores (unknown). It cannot
perform a save operation.". No last error recorded.
An uncaught exception was raised
This NSPersistentStoreCoordinator has no persistent stores (unknown). It
cannot perform a save operation.
(
0 CoreFoundation 0x00007fff8569b66c
__exceptionPreprocess + 172
1 libobjc.A.dylib 0x00007fff87dfd76e
objc_exception_throw + 43
2 CoreData 0x00007fff898b7eb3
-[NSPersistentStoreCoordinator
_coordinator_you_never_successfully_opened_the_database_so_saving_back_to_it_is_kinda_hard:]
+ 51
3 CoreData 0x00007fff898b810d
-[NSPersistentStoreCoordinator _introspectLastErrorAndThrow] + 77
4 CoreData 0x00007fff898b8236
__65-[NSPersistentStoreCoordinator
executeRequest:withContext:error:]_block_invoke + 166
5 CoreData 0x00007fff898c331b
gutsOfBlockToNSPersistentStoreCoordinatorPerform + 171
6 libdispatch.dylib 0x0000000100025d43
_dispatch_client_callout + 8
7 libdispatch.dylib 0x00000001000270b1
_dispatch_barrier_sync_f_invoke + 348
8 CoreData 0x00007fff898b2312 _perform +
194
9 CoreData 0x00007fff89804395
-[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 533
10 CoreData 0x00007fff898043c4
-[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 580
11 CoreData 0x00007fff8982eb3b
-[NSManagedObjectContext save:] + 1291
12 Image Chest 0x0000000100002291 -[Document
unsafeSaveContext:] + 113
13 Image Chest 0x000000010000213a
__24-[Document saveContext:]_block_invoke + 42
14 CoreData 0x00007fff8984a246
developerSubmittedBlockToNSManagedObjectContextPerform + 182
15 libdispatch.dylib 0x0000000100025d43
_dispatch_client_callout + 8
16 libdispatch.dylib 0x0000000100029fb3
_dispatch_queue_drain + 1804
17 libdispatch.dylib 0x000000010002bfc0
_dispatch_queue_invoke + 223
18 libdispatch.dylib 0x0000000100028f5e
_dispatch_root_queue_drain + 666
19 libdispatch.dylib 0x000000010003acd0
_dispatch_worker_thread3 + 106
20 libsystem_pthread.dylib 0x00007fff92a82637
_pthread_wqthread + 729
21 libsystem_pthread.dylib 0x00007fff92a8040d
start_wqthread + 13
)
The save model is based on Jerry's YaBT sample mentioned earlier in the thread,
which has a rootContext (NSPrivateQueueConcurrencyType), mainContext
(NSMainQueueConcurrencyType), and tempContext (NSPrivateQueueConcurrencyType)
in a chain of children. I'm guessing it's because the document has not been
saved to disk yet, whereas the YaBT sets up a file for the persistent store
when it creates it. Since the document sets up the store, I don't know what I'd
do in this case.
Ugh. This needs to be more complicated and harder to comprehend.
--
Steve Mills
Drummer, Mac geek
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