Question

I’m displaying a dynamic list of names in a table view, and I’m trying to split them into sections according to the first letter of the name…

I’ve created an array with an alphabetical list of letters

charIndex = [[NSMutableArray alloc] init];

for(int i=0; i<[appDelegate.children count]-1; i++)
{
    // get the person
    Child *aChild = [appDelegate.children objectAtIndex:i];

    // get the first letter of the first name
    NSString *firstLetter = [aChild.firstName substringToIndex:1];

    NSLog(@"first letter: %@", firstLetter);

    // if the index doesn't contain the letter
    if(![charIndex containsObject:firstLetter])
    {
        // then add it to the index
        NSLog(@"adding: %@", firstLetter);
        [charIndex addObject:firstLetter];
    }
}

and I’ve set up the number of sections and title

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // set the number of sections in the table to match the number of first letters
    return [charIndex count];
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    // set the section title to the matching letter
    return [charIndex objectAtIndex:section];
}

But I’m having trouble with what should be in

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{

}

Answer 1

You could add a dictionary that keeps track of the number of people that share the same first letter. Quick untested code:

charIndex = [[NSMutableArray alloc] init];
charCount = [[NSMutableDictionary alloc] init];

    for(int i=0; i<[appDelegate.children count]-1; i++)
    {
        // get the person
        Child *aChild = [appDelegate.children objectAtIndex:i];

        // get the first letter of the first name
        NSString *firstLetter = [aChild.firstName substringToIndex:1];

        NSLog(@"first letter: %@", firstLetter);

        // if the index doesn't contain the letter
        if(![charIndex containsObject:firstLetter])
        {
            // then add it to the index
            NSLog(@"adding: %@", firstLetter);
            [charIndex addObject:firstLetter];
            [charCount setObject:[NSNumber numberWithInt:1] forKey:firstLetter];
        }
        [charCount setObject:[NSNumber numberWithInt:[[charCount objectForKey:firstLetter] intValue] + 1] forKey:firstLetter];
    }

Then in:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    [charCount objectForKey:[charIndex objectAtIndex:section]];
}