Question

I have the following code:

//in .h file: NSMutableDictionary* expandedSections;
//in Init method: expandedSections = [[NSMutableDictionary alloc] init];

- (void) tableView:(UITableView*)tableView didSelectRowAtIndexPath:(NSIndexPath*)indexPath
{
    NSString* key = [NSString stringWithFormat:@"%d", indexPath.row];
    NSLog(@"Key: %@", key);
    if ([expandedSections objectForKey:key] == nil)
    {
        NSLog(@"Value Should be: %@", [NSNumber numberWithBool:YES]);
        [expandedSections setObject:[NSNumber numberWithBool:YES] forKey:key];
    }
    else
    {
        [expandedSections setObject:[NSNumber numberWithBool:![[expandedSections objectForKey:key] boolValue]] forKey:key];
    }
    NSLog(@"Value: %@", [expandedSections objectForKey:key]);
    [tableView beginUpdates];
    [tableView endUpdates];
}

- (float) tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString* key = [NSString stringWithFormat:@"%d", indexPath.row];
    NSLog(@"Key: %@", key);
    NSLog(@"Value: %@", [expandedSections objectForKey:key]);
    if ([expandedSections objectForKey:key] == nil || ![[expandedSections objectForKey:key] boolValue])
    {
        return 44;
    }
    else
    {
        return 88;
    }
}

I’m expecting this to output to the log an alternating value of 1 and 0 when I tap a row in my UITableView. And correspondingly, expand and collapse the row I tap.

For some reason, the NSDictionary, never has any key/value pairs in it, so as a consequence the rows never expand. THe logging from heightForRow method comes out as:

2012-02-08 11:36:30.291 MappApp[5040:707] Key: 0
2012-02-08 11:36:30.293 MappApp[5040:707] Value: (null)

The logging from didSlectRowAt method comes out as:

2012-02-08 11:36:44.551 MappApp[5040:707] Key: 0
2012-02-08 11:36:46.530 MappApp[5040:707] Value Should be: 1
2012-02-08 11:36:50.723 MappApp[5040:707] Value: (null)

What am I doing wrong?

Answer 1

The logging output makes sense if expandedSections is nil, i.e. you never created it or reset it for some reason.

You should start by checking the initialization code for your class.