Question

Struggling a bit here…

My view controller adheres to following protocols

In my init method I will check a remote server to get an updated XML file… parse the XML file, and write the contents to Core Data.

My tableview’s content is managed with NSFetchedResultsController that displays this Core Data.

My Problem:

NSFetchedResultsController seems to be getting the data before the Core Data update from the remote file takes place. I’ve verified the database is being updated properly and if I run a second time the TableView will show the correct data.

Maybe I’m just not doing the reloadData in the proper place? I have implemented

-(void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [myTableView reloadData];
}

Also, after the parser completes and the new data has been written to core data I’m trying this:

-(void)parserDidEndDocument:(NSXMLParser *)parser {
     [myTableView reloadData];  
}

Anyone have any ideas? Let me know what extra code might be useful to post. Thanks!

Answer 1

you may want to check the following (from Apple’s docs)

A controller thus effectively has three modes of operation, determined by whether it has a delegate and whether the cache file name is set.

1. No tracking: the delegate is set to nil.
   The controller simply provides access to the data as it was when the fetch was executed.

2. Memory-only tracking: the delegate is non-nil and the file cache name is set to nil.
   The controller monitors objects in its result set and updates section and ordering information in response to relevant changes.

3. Full persistent tracking: the delegate and the file cache name are non-nil.
   The controller monitors objects in its result set and updates section and ordering information in response to relevant changes. The controller maintains a persistent cache of the results of its computation.

it sounds like you want full persistent tracking. So you probably want to make sure you have the delegate set (which you probably already have done) and set the cache to non nil

You may also want to make sure you are saving your managedObjectContext after you are done parsing. After saving, make sure to perform the fetch again.

NSError *error;
BOOL success = [controller performFetch:&error];
if (!success)
  NSLog(@"Core Data Fetch Error:  %@"error);

It could be that the app is saving the context when it is exiting and that is why you are seeing the data when you relaunch.

Good luck