This is a Cocoa Touch question. Is this list also for Cocoa Touch?
I can't manage to solve a crash that occurs with a very limited modification to
a project as generated by XCode.
When adding two (or more) objects to an empty store rather than one, when using
sections, Cocoa Touch crashes with an array out-of-bound exception.
I have spent a large number of hours on this, but I am going nowhere, so maybe
someone here has an idea.
To reproduce the crash:
1- Start with a Navigation-based application project using Core Data. I named
it crashTest.
2- The template has one Entity in the data model, called Event. Add two strings
attributes to it. I added "name" and "kind".
3- Modify RootViewController.m to use sections on the new "kind" attribute. to
do so change one line in - (NSFetchedResultsController
*)fetchedResultsController:
NSFetchedResultsController *aFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:managedObjectContext sectionNameKeyPath:nil
cacheName:@"Root"];
to:
NSFetchedResultsController *aFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:managedObjectContext sectionNameKeyPath:@"kind"
cacheName:@"Root"];
Also, one data source routine must be added to name the section:
- (NSString *)tableView:(UITableView *)tableView
titleForHeaderInSection:(NSInteger)section {
return [[[fetchedResultsController sections] objectAtIndex:section] name];
}
4- Modify the - (void)insertNewObject routine to create two objects at once,
and to set the two new attributes:
- (void)insertNewObject {
// Create a new instance of the entity managed by the fetched results
controller.
NSManagedObjectContext *context = [fetchedResultsController
managedObjectContext];
NSEntityDescription *entity = [[fetchedResultsController fetchRequest]
entity];
NSManagedObject *newManagedObject = [NSEntityDescription
insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
// If appropriate, configure the new managed object.
[newManagedObject setValue:[NSDate date] forKey:@"timeStamp"];
[newManagedObject setValue:@"name1" forKey:@"name"];
[newManagedObject setValue:@"lunch" forKey:@"kind"];
newManagedObject = [NSEntityDescription
insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
[newManagedObject setValue:[NSDate date] forKey:@"timeStamp"];
[newManagedObject setValue:@"name2" forKey:@"name"];
[newManagedObject setValue:@"lunch" forKey:@"kind"];
// Save the context.
NSError *error = nil;
if (![context save:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
}
5- Run, tap the "+" button, and watch it crash:
2010-03-15 02:48:30.056 crashTest[12767:207] Serious application error.
Exception was caught during Core Data change processing: *** -[NSCFArray
objectAtIndex:]: index (1) beyond bounds (1) with userInfo (null)
At this point, I am thinking about a bug in Cocoa Touch. But I may also have
overseen something. What?
In any case, the only workaround I found is to setup a flag to YES (say
"massUpdate"), and in the four delegate routines, test for this flag. If set do
nothing, except reload the whole table view data instead of calling endUpdate.
Many thanks,
Jean-Denis
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