Joanna,
That worked perfectly. Thanks for taking the time to help me out -- it always
bugs me when something takes 10 extra steps and I have a gut feeling it can be
done in one. mergeChangesFromContextDidSaveNotification: was the key to making
the changes from the second context a simple thing to accomplish.
The tutorial was great, very well put together.
Austin
On Mar 22, 2010, at 5:58 AM, Joanna Carter wrote:
> Hi Austin
>
>> Thank you Joanna, that was very helpful. So, from your experience,
>> mergeChangesFromContextDidSaveNotification: will not pick up adding a new
>> object, just editing an existing one? It seems like the real pain point is
>> having to re-create the new object in the second managedObjectContext and
>> copy all it's properties.
>
> My tutorial is meant to demonstrate several different techniques, to give
> people an idea of what is available, especially if they are coming from a
> different programming language.
>
> I included the routine for copying the object contents, possibly because I
> too came across Tim Isted's blog and, at the time, thought that was what was
> necessary to ensure that object properties were populated from the correct
> MOC.
>
> However, I have just checked and found that you can, indeed, use the same
> methodology for both editing and adding a new object. Here is some revised
> code that you can use in place of the sheetDidEnd:returnCode:contextInfo:
> method in the tutorial.
>
> - (void) sheetDidEnd:(NSWindow *)sheet returnCode:(int)returnCode
> contextInfo:(void *)contextInfo
> {
> // we are only interested in doing something with the edited word
> // if the Save button was pressed
> if (returnCode == NSOKButton)
> {
> NSNotificationCenter *dnc = [NSNotificationCenter defaultCenter];
>
> [dnc addObserverForName:NSManagedObjectContextDidSaveNotification
> object:managedObjectContext
> queue:nil
> usingBlock:^(NSNotification *saveNotification)
> {
> [[sourceListController managedObjectContext]
> mergeChangesFromContextDidSaveNotification:saveNotification];
>
> [sourceListController fetch:nil];
> }];
>
> NSError *error;
>
> if (![managedObjectContext save:&error])
> {
> NSLog(@"Error saving edited Word");
> }
>
> [dnc removeObserver:self
> name:NSManagedObjectContextDidSaveNotification
> object:managedObjectContext];
> }
> else
> {
> // Cancel button pressed -
> // rollback any changes to the temporary context
> [managedObjectContext rollback];
> }
>
> // close the dialog
> [sheet orderOut:self];
>
> // clear temporary object from controller
> [wordController setContent:nil];
> }
>
> The only real difference here is that, within the callback block, you need to
> call [sourceListController fetch:nil] to ensure that the original browsing
> list is not just refreshed but that the sort descriptors are honoured to
> include the new object.
>
> Regards
>
> Joanna
>
> --
> Joanna Carter
> Carter Consulting
>
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