Question

I have an NSArray of objects:

MyObject consists of the following string properties:

Title
Category
Name

There are a total of 9 categories.

I would like to display these categories sectioned in a UITableView.

At the moment my code looks like this, but it’s not quite right and I’m unsure of how to handle the individual categories in my

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;` as well.

    for (ArrayOfMyObject *item in myArray) {
      if ([item.Category isEqualToString:@"Category1"]) {
        NSDictionary *dict = [NSDictionary dictionaryWithObjects:item forKey:item.Category];
        [self.itemsArray addObject:dict];
      }

      if ([item.Category isEqualToString:@"Category2"]) {
        NSDictionary *dict = [NSDictionary dictionaryWithObjects:item forKey:item.Category];
        [self.itemsArray addObject:dict];
      }
      ... (etc, for the rest of the Category titles).
    }

I should be getting a total of 9 sections if there’s 9 categories, but it looks like I’m actually getting the total count of items (there’s like 76). Any help would be greatly appreciated and feel free to request more code if need-be.

I guess I would also need to know how to handle this inside the cellForRowAtIndexPath method.

Would I do something like this?

MyObject *item = (MyObject *)[self.itemsArray objectAtIndex:indexPath.row];
NSMutableDictionary *dictionary = [self.itemsArray objectAtIndex:indexPath.section];
NSArray *categoryArray = [dictionary objectForKey:item.Category];

Answer 1

I’d start by organising your data source in a different way.

Get a datasource NSArray that contains 9 NSDictionaries representing your categories. Inside each category, you have a couple of keys – one for a corresponding string with the category name and one for a corresponding array of MyObjects that belong to the category:

dataSource [
             item1 {
                     catName = @"CategoryName 1"
                     objects = NSArray of MyObjects for catName1
                   }
             item2 {
                     catName = @"CategoryName 2"
                     objects = NSArray of MyObjects for catName2
                   }
             etc...
           ]

Once you have the data organised this way, your datasource methods for the table view will look like this (conceptually):

numberOfSections can be accessed with [datasource count]

titleForSection can be accessed with [[datasource objectAtIndex:indexPath.section] valueForKey:@"catName"]

numberOfRowsInSection can be accessed with [[[datasource objectAtIndex:indexPath.section] valueForKey:@"objects"] count]

And finally, the MyObject for each row can be accessed with [[[datasource objectAtIndex:indexPath.section] valueForKey:@"objects"] objectAtIndex:indexPath.row] on the cellForRowAtIndexPath: method.

Makes sense?
Let me know if you have any questions.
Cheers,
Rog

[EDIT TO ANSWER YOUR FOLLOW UP QUESTION]

This is based on a few assumptions but you should get the gist of it. For the purpose of testing this, I created a MyObject class that returns an instance with random generated category names.

- (void)createDatasource
{
    NSInteger numberOfObjects = 10;
    NSMutableArray *objects = [NSMutableArray arrayWithCapacity:numberOfObjects];
    NSMutableArray *categories = [NSMutableArray arrayWithCapacity:numberOfObjects];
    for (int i = 0; i < numberOfObjects; i++)
    {
        MyObject *obj = [[MyObject alloc] init];
        [objects addObject:obj];
        [categories addObject:obj.category];
        [obj release];
    }
    NSSet *set = [NSSet setWithArray:categories];
    NSMutableArray *dataSource = [[NSMutableArray alloc] initWithCapacity:[set count]];
    for (NSString *categoryString in set)
    {
        NSMutableDictionary *mainItem = [[NSMutableDictionary alloc] initWithObjectsAndKeys:nil, @"categoryName", nil, @"myObjects", nil];
        NSMutableArray *mainItemMyObjects = [NSMutableArray array];
        [mainItem setValue:categoryString forKey:@"categoryName"];
        for (MyObject *obj in objects)
        {
            if ([obj.category isEqualToString:categoryString])
            {
                [mainItemMyObjects addObject:obj];
            }
        }
        [mainItem setValue:mainItemMyObjects forKey:@"myObjects"];
        [dataSource addObject:mainItem];
        [mainItem release];
    }
    NSLog (@"objects = %@\ncategories = %@\nset = %@\ndatasource = %@", objects, categories, set, dataSource);
    // Use and release your datasource as appropriate
    // You may want to sort your datasource appropriately depending on your needs
}