Getting an NSDictionary by filtering another NSDictionary

Question

Hope someone could help me with that :

I'm using a NSDictionary to fill a UITableView. Its model is like [key:userID => value:userName]. The tableView is only filled with userName but when clicked, it has to send the userID related. The problem comes when I want to filter the UITable. I only found the way to filter a Dictionary by transforming it into NSArray (using Predicate) but it make me loose the relation between userNames and userIDs.

A solution would be to filter the initial NSDictionary to get a filtered NSDictionary (with still the relational key/value), but I don't know how to do that. I only found solutions to get Arrays.

How could I do that, or is there a better solution to do it?

Answer 1

There is a much better solution, François. Create, from your NSDictionary (I will call it here myDictionary), an NSArray like this (declare it in your interface file):

NSArray *arrayForTableView;

Then, just after you load your NSDictionary, do the following:

arrayForTableView = [myDictionary allKeys]; // so you will have an array of all UserID's

Now, in your tableView: cellForRowAtIndexPath: method, you can do it like this:

cell.textLabel.text = [myDictionary objectForKey:[arraForTableView objectAtIndex:indexPath.row]];

And then, when you will want to pass the userID when the user selects the cell, in your tableView: didSelectRowAtIndexPath: you just do it this way:

id userIDSelected = [arraForTableView objectAtIndex:indexPath.row];

Then, when you want to filter the array according to the search, you can simply recreate your arrayForTableView, by "scanning" your NSDictionary this way:

NSString *typedString;
NSMutableArray *arrayFiltered = [NSMutableArray array];
for (int i = 0; i < [[myDictionary allKeys] count]; i++)
{
    if ([[myDictionary objectForKey:[[myDictionary allKeys] objectAtIndex:i]] rangeOfString:typedString].location != NSNotFound)
    {
        [arrayFiltered addObject:[[myDictionary allKeys] objectAtIndex:i]];
    }
}

arrayForTableView = arrayFiltered;

This way, you won't even need to change your UITableView dataSource and delegate methods.