Question

I have a UITableView that is configured for a subtitle cell. When I add a cell to the TableView I have two arrays. One for the subtitle and the other for the main label. I also have an NSMutableDictionary so that when I add the cell to the table it records an object and a key. My problem is when I want to delete the cell from the UITableView I use this method:

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
    [myArray removeObjectAtIndex:indexPath.row];
    [numberArray removeObjectAtIndex:indexPath.row];


    [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
} else if (editingStyle == UITableViewCellEditingStyleInsert) {
    // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
}
}

This works great for removing the objects from their associated arrays, but I also want to remove the objects from the MutableDictionary I made. I thought that you would use somethings similar to what I used with the arrays.

[myArray removeObjectAtIndex:indexPath.row];

But I can’t use

 [myDictionary removeObjectForKey:indexPath.row];

Does anyone know how I would write this?

Answer 1

Since indexPath.row is a primitive type, it cannot be used as a key in NSDictionary: you need to wrap it in NSNumber in order to do so.

[myDictionary removeObjectForKey:[NSNumber numberWithInt:indexPath.row]];

This would work only if you use NSNumber-wrapped integers as keys in your NSMutableDictionary. In general, since NSDictionary is an associative container, you need to use the same key in the calls of removeObjectForKey as you used in the calls of setObject:forKey:.