objective c - Fetching Core Data related Entities properties -

i have 2 many-to-many related entities, customer , city , nsmanagedobject subclasses generated them. have relationship customer city called cities. in city there property called city. trying fetch entity customer simple fetchresultscontroller:

-(nsfetchedresultscontroller *) fetchedresultscontroller {    if (_fetchedresultscontroller != nil)   {       return _fetchedresultscontroller;   }   self.managedobjectcontext = [[ptdatamanager sharedmanager] managedobjectcontext];   nsfetchrequest *fetchrequest = [[nsfetchrequest alloc] init];   nsentitydescription *entity = [nsentitydescription entityforname:@"customer"                                             inmanagedobjectcontext:[self managedobjectcontext]];   [fetchrequest setentity:entity];    _fetchedresultscontroller = [[nsfetchedresultscontroller alloc] initwithfetchrequest:fetchrequest                                                                  managedobjectcontext:self.managedobjectcontext                                                                    sectionnamekeypath:nil                                                                             cachename:nil];   _fetchedresultscontroller.delegate = self;    return _fetchedresultscontroller;  } 

as result retrieving fine except cities property ((null) value) predicate

@"cities.name contains[cd] %@" 

in customer subclass can use method:

-(city *)city  {   return (cdcities *)[[ptdatafetchhelper sharedinstance] entityforname:@"city"                                                           withserverid:self.city_server_id                                                              incontext:[self managedobjectcontext]];  } 

and retrieving city-values fine, way slows down ui (displaying data in tableview).
so, questions:

• if perform basic fetch this, retrieve values of specified entity only, or values related entities too?
• if need additional predicate, how can modify fetch city properties city entity?

a fetch request fetches 1 entity type. if fetch customer, customers. can traverse core data relationships without doing additional fetch requests. ask customer instance value of cities attribute. 0 or more city instances, , can ask each 1 of city attribute.

i'm not sure you're getting @ @"cities.city [cd]". that's not predicate. part of predicate, doesn't match city attribute against anything. it's 1 side of equation.