iphone - NSFetchedResultsController with a one-to-many relationship -


i'm looking display data core data model in uitableviewcontroller. model has 2 entities, one-to-many relationship. want items many entity rows, broken down sections one. in event no rows exist, still want section header display.

i have working nsfetchedresultscontroller table working many table only, need expand one-to-many relationship. i'm having no luck making work, , haven't found examples on how this.

the table display items, not subset.

any suggestions?

since didn't provide details model objects using, example use following model.

library <-->> book

the first thing suggest doing @ documentation nsfetchedresultscontroller, initwithfetchrequest:managedobjectcontext:sectionnamekeypath:cachename:. tells need know fetching data sections.

the important part first sort descriptor must return similar order sectionnamekeypath.

nsfetchrequest *fetchrequest = [nsfetchrequest fetchrequestwithentityname:@"book"];  nssortdescriptor *librarysort = [[nssortdescriptor alloc] initwithkey:@"name" ascending:yes]; nssortdescriptor *booksort = [[nssortdescriptor alloc] initwithkey:@"title" ascending:yes]; [fetchrequest setsortdescriptors:@[librarysort, booksort]];  nsfetchedresultscontroller *controller = [[nsfetchedresultscontroller alloc] initwithfetchrequest:fetchrequest                                                                              managedobjectcontext:context                                                                                sectionnamekeypath:@"library.name"                                                                                         cachename:nil];

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