Is it possible to get great results when using NSFetchedResultsController?

Question

I have a search for a product that searches the ProductCategories where my products are located, sometimes my products are in several categories, which gives me duplicate results. I do not want to look for the product table directly, because there are several products that have several sizes, but basically are the same product.

Is there a way to get various search results using NSFetchedResultsController?

Answer 1

Yes, you can...

pay attention to the method

- (NSFetchedResultsController *)fetchedResultsController; 

and add the following lines there (in this example we get only a separate "title" attribute of our managed objects):

 [fetchRequest setReturnsDistinctResults:YES]; [fetchRequest setResultType:NSDictionaryResultType]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObject:@"title"]]; self.fetchedResultsController.delegate = nil; 

you need to take care of how you access the values ​​from NSFetchedResultsController ... For example, in

 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath; 

use the following code to access the data:

 NSDictionary* title = [self.fetchedResultsController objectAtIndexPath:indexPath]; cell.textLabel.text = [title objectForKey:@"title"]; 

Answer 2

In addition to the solution that Shingoo provided, be sure to set the NSFetchedResultsController delegate to nil to disable automatic updates that will not work with NSDictionaryResultType and various values:

 self.fetchedResultsController.delegate = nil; 

Answer 3

You will need to use NSPredicate (see Predicate Programming Guide )

It is complicated, but you can do it using SUBQUERY

Answer 4

When creating NSFetchRequest you can use -setReturnsDistinctResults: and set it to YES .