Question

I have a many to many and would like to sort this so that (Event)title is the keyPath listing associated (Person)name below, including duplicates when is the case. something like this.

data model description
Event <<—->> Person, inverse relationships are ‘events’ and ‘people’ each with a single attribute eventTitle and personName.

eventTitle1
personNameA
personNameB
eventTitle2
personNameA
personNameC

I’ve worked with to-one fetchRequests and sorted on keyPath with sortDescriptors. what needs to be done differently for the to many to work this way. Is that enough information? First post, any/ all assistance very appreciated.

Answer 1

I would get the fetch request to get the “Person” entity, and sort by event then person. Sort of like this.

NSSortDescriptor *eventSortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"event.name" 
                                                                     ascending:ascending 
                                                                      selector:@selector(caseInsensitiveCompare:)];

NSSortDescriptor *personSortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name"
                                                                    ascending:ascending 
                                                                     selector:@selector(caseInsensitiveCompare:)];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:eventSortDescriptor, personSortDescriptor, nil];


NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" 
                                          inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setSortDescriptors:sortDescriptors];

NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest 
                                                                                            managedObjectContext:self.managedObjectContext 
                                                                                              sectionNameKeyPath:@"event.name"
                                                                                                       cacheName:cacheName];