StackOverflow2013

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POios: NSFetchRequest and filtering
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copied!<p>I have a NSFetchRequest (executing in a NSFetchedResultsController) for the following data:</p> <pre><code>Person (one-to-many) Encounter </code></pre> <p>Encounter has an int field "type". In my tableView, I want to show:</p> <pre><code>Person A - Encounter of type 1 Person A - Encounter of type 2 Person B - Encounter of type 1 </code></pre> <p>etc. That is, for a Person, I only want one Encounter of each type. Is there a way to do that in a Core Data query? I could do this with code to filter the result of an NSFetchRequest, but then I couldn't use NSFetchedResultsController.</p> <p>[EDIT]</p> <p>Here's the code I'm currently trying. The result is several Encounters with the same type for one Person.</p> <pre><code>NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; // entity NSEntityDescription *entity = [NSEntityDescription entityForName:@"Encounter" inManagedObjectContext:self.managedObjectContext]; [fetchRequest setEntity:entity]; // return distinct NSDictionary *entityProperties = [entity propertiesByName]; [fetchRequest setPropertiesToFetch:[NSArray arrayWithObjects: [entityProperties objectForKey:@"person"], [entityProperties objectForKey:@"type"], nil]]; [fetchRequest setReturnsDistinctResults:YES]; [fetchRequest setResultType:NSDictionaryResultType]; NSError *error; NSArray *fetchedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error]; for (NSDictionary *d in fetchedObjects) { NSLog(@"NSDictionary = %@", d); } [fetchRequest release]; </code></pre>

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