In case anyone else hits this, I 'solved' it by setting a merge policy on the
managed object context:
[_managedObjectContext setMergePolicy:[[NSMergePolicy alloc]
initWithMergeType:NSMergeByPropertyObjectTrumpMergePolicyType]];
This very much feels like a workaround. According to the documentation
-------
Problem: You see the error message, "Could not merge changes".
Cause: Two different managed object contexts tried to change the same data.
This is also known as an optimistic locking failure.
Remedy: Either set a merge policy on the context, or manually
(programmatically) resolve the failure. You can retrieve the currently
committed values for an object usingcommittedValuesForKeys:, and you can
re-fault the object (so that when it is next accessed its data values are
retrieved from its persistent store) usingrefreshObject:mergeChanges:.
-------
Still, I wonder why this happens in 10.9 but not in 10.6-10.8.
Cheers,
Martin
On 25 Oct 2013, at 08:46 pm, Martin Hewitson <martin.hewit...@aei.mpg.de> wrote:
> Dear list,
>
> I have two different core data apps, both of which are exhibiting similar
> behaviour in that they sometimes (for some changes in some properties) can’t
> save the MOC. Here is an example error I get when using
>
> [moc save:error]
>
> Error Domain=NSCocoaErrorDomain Code=133020 "Could not merge changes."
> UserInfo=0x7feb8e2edf90 {conflictList=(
> "NSMergeConflict (0x7feb8e2d68b0) for NSManagedObject (0x7feb8e07d610)
> with objectID '0x54000ab
> <x-coredata://DE6DE351-C155-4C70-A1CB-3BFEAA0AE69C/Theme/p21>' with
> oldVersion = 22 and newVersion = 23 and old object snapshot = {\n color =
> <62706c69 73743030 d4010203 04050615 16582476 65727369 6f6e5824 6f626a65
> 63747359 24617263 68697665 72542474 6f701200 0186a0a3 07080f55 246e756c
> 6cd3090a 0b0c0d0e 554e5352 47425c4e 53436f6c 6f725370 61636556 24636c61
> 73734f10 28302e37 30353838 32333730 3520302e 31313736 34373035 39332030
> 2e303339 32313536 38373636 00100180 02d21011 12135a24 636c6173 736e616d
> 65582463 6c617373 6573574e 53436f6c 6f72a212 14584e53 4f626a65 63745f10
> 0f4e534b 65796564 41726368 69766572 d1171854 726f6f74 80010811 1a232d32
> 373b4148 4e5b628d 8f9196a1 aab2b5be d0d3d800 00000000 00010100 00000000
> 00001900 00000000 00000000 00000000 0000da>;\n name = Discussion;\n} and
> new cached row = {\n color = <62706c69 73743030 d4010203 04050615 16582476
> 65727369 6f6e5824 6f626a65 63747359 24617263 68697665 72542474 6f701200
> 0186a0a3 07080f55 246e756c 6cd3090a 0b0c0d0e 554e5352 47425c4e 53436f6c
> 6f725370 61636556 24636c61 73734f10 28302e37 30353838 32333730 3520302e
> 31313736 34373035 39332030 2e303339 32313536 38373636 00100180 02d21011
> 12135a24 636c6173 736e616d 65582463 6c617373 6573574e 53436f6c 6f72a212
> 14584e53 4f626a65 63745f10 0f4e534b 65796564 41726368 69766572 d1171854
> 726f6f74 80010811 1a232d32 373b4148 4e5b628d 8f9196a1 aab2b5be d0d3d800
> 00000000 00010100 00000000 00001900 00000000 00000000 00000000 0000da>;\n
> name = Discussion;\n}"
> )}
>
> Both apps are fairly bog-standard core data shoe box apps which have been
> working fine since 10.6. These problems just started to appear on 10.9.
>
> Any ideas what I can try or what might have changed to cause these problems?
>
> Many thanks,
>
> Martin
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