UITableView reloadData loads old data

Question

Beginner iPhone programmer here, so bear with me.

Here's the problem: I have a UITableView. I also have a search controller. When the text in the search bar changes, it calls the reloadData method which adds getDataInBackground to the NSOperationQueue. Once the operation is done, it calls [tableView reloadData] in the main thread. Here's the code:

- (void)reloadData{
    if(activityLabel.superview == nil) //show activity label
        [self.view addSubview:activityLabel];

    NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(getDataInBackground) object:nil];
    [queue cancelAllOperations];
    [queue addOperation:operation];
    [operation release];
}

- (NSPredicate *)getPredicate{
    /* Sets up the appropriate predicate using search term and filters, returns it */
}

- (void)getDataInBackground{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    NSManagedObjectContext *context = [(FitAmp_LibraryAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
    NSError *error;
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"ExerciseListInfo" inManagedObjectContext:context];
    [fetchRequest setEntity:entity];

    [fetchRequest setPredicate:[self getPredicate]];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"title" ascending:YES];   
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
    [fetchRequest setSortDescriptors:sortDescriptors];

    NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];

    NSMutableDictionary *tempExercises = [[NSMutableDictionary alloc] init];
    NSString *firstLetter;
    NSMutableArray *exercisesSection;
    for (ExerciseListInfo *exercise in fetchedObjects) {
        firstLetter = [[exercise.title substringToIndex:1] uppercaseString];
        if([[NSScanner scannerWithString:firstLetter] scanInteger:NULL])
            firstLetter = @"#";

        exercisesSection = [tempExercises objectForKey:firstLetter];
        if(exercisesSection == nil){
            NSMutableArray *newExerciseArray = [[NSMutableArray alloc] initWithObjects:exercise, nil];
            [tempExercises setObject:newExerciseArray forKey:firstLetter];
            [newExerciseArray release];
        }else{
            [exercisesSection addObject:exercise];
        }
        exercisesSection = nil;
    }

    NSMutableArray *tempSectionsArray = [[tempExercises allKeys] mutableCopy];

    self.exercisesSections = (NSMutableArray *)[tempSectionsArray sortedArrayUsingSelector:@selector(compare:)];
    self.exercises = tempExercises;

    [tempSectionsArray release];
    [tempExercises release];

    [self.tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];

    if(activityLabel.superview)
        [activityLabel performSelectorOnMainThread:@selector(removeFromSuperview) withObject:nil waitUntilDone:YES];

    [self performSelectorOnMainThread:@selector(printExercises) withObject:nil waitUntilDone:YES];

    [fetchRequest release]; 
    [sortDescriptor release];
    [sortDescriptors release];

    [pool drain];
}

The problem is that when the table reloads data, it appears to use the [self exercises] and [self exercisesSections] from the last time getDataInBackground ran. The value of the 2 objects are current and correct after every search (I print them out with NSLog) but tableView seems to be using an outdated copy.

What do I do?

EDIT: It seems like if I retain self.exercises and self.exercisesSections after I set them, the problem goes away. But then aren't I leaking memory?

Answer 1

Here is what I guess that can help you. Double check that the table view is reloaded.

You can put nslog or breakpoint inside the tableView:cellForRowAtIndexPath: to check for 2 things:

1/ the table view is actually reloaded.

2/ Check the value of excerises exactly at that point