Objective C - NSFetchRequest with category unique - objective-c

Question

I'm using Core Data for my iPhone app.
Initially I have a UITableViewController that just lists all the "Stores".
However, now we realized that list is getting too long, and would like to break it down into 2 layers of UITableViewController. The first one being "States" and the 2nd being the stores in the selected State.
I figured out how to grab all stores in a certain State
[fetchRequest setPredicate:[NSPredicate predicateWithFormat:#"state.abbreviation == 'AA'"]];
How can I using NSFetchRequest, just to grab the list of States? Something like this sql statement maybe? Is it possible?
SELECT DISTINCT abbreviation FROM Stores;
Below is my Model (simplified)
Store.h
#class State;
#interface Store : ManagedAppObject {
#private
}
#property (nonatomic, retain) NSString * title;
#property (nonatomic, retain) State * state;
#end
State.h
#interface State : ManagedAppObject {
#private
}
#property (nonatomic, retain) NSString * abbreviation;
#property (nonatomic, retain) NSString * name;
#end
Thank you,
Tee

Answer 1

To get unique results you'd usually use
fetchRequest.propertiesToFetch = [NSArray arrayWithObject:#"<#propertyName#>"];
fetchRequest.returnsDistinctResults = YES;
fetchRequest.resultType = NSDictionaryResultType;
But unless I'm missing something here, that's probably not what you should do. Why don't you just set your fetchRequest to fetch State entities in the first place? Then use the state.stores relation (which hopefully you have modeled as the inverse of store.state) to get the data for your second 'layer' tableView.