objective c - fetch data from a RESTful API into Core Data -

hello can t fetch localdatabase json restapi

i want data website : http://barcelonaapi.marcpous.com/bus/stations.json

i'm using restkit 0.20

here code in appdelegate :

 - (bool)application:(uiapplication *)application didfinishlaunchingwithoptions:(nsdictionary *)launchoptions {     nsurl *baseurl = [nsurl urlwithstring:@"http://barcelonaapi.marcpous.com/bus/stations.json"];     rkobjectmanager *objectmanager = [rkobjectmanager managerwithbaseurl:baseurl];
  // initialize managed object model bundle nsmanagedobjectmodel *managedobjectmodel = [nsmanagedobjectmodel mergedmodelfrombundles:nil]; // initialize managed object store rkmanagedobjectstore *managedobjectstore = [[rkmanagedobjectstore alloc] initwithmanagedobjectmodel:managedobjectmodel]; objectmanager.managedobjectstore = managedobjectstore;  // complete core data stack initialization [managedobjectstore createpersistentstorecoordinator]; nsstring *storepath = [rkapplicationdatadirectory() stringbyappendingpathcomponent:@"busdb.sqlite"]; nsstring *seedpath = [[nsbundle mainbundle] pathforresource:@"rkseeddatabase" oftype:@"sqlite"]; nserror *error; nspersistentstore *persistentstore = [managedobjectstore addsqlitepersistentstoreatpath:storepath fromseeddatabaseatpath:seedpath withconfiguration:nil options:nil error:&error]; nsassert(persistentstore, @"failed add persistent store error: %@", error);  // create managed object contexts [managedobjectstore createmanagedobjectcontexts];  // configure managed object cache ensure not create duplicate objects managedobjectstore.managedobjectcache = [[rkinmemorymanagedobjectcache alloc] initwithmanagedobjectcontext:managedobjectstore.persistentstoremanagedobjectcontext];  //------------------------end initilize restkit--------------------------------   rkentitymapping *buslistmapping = [rkentitymapping mappingforentityforname:@"bus" inmanagedobjectstore:managedobjectstore]; buslistmapping.identificationattributes = @[ @"streetname" ];  [buslistmapping addattributemappingsfromdictionary:  @{    @"id":            @"busid",    @"street_name":   @"streetname",    @"city":          @"city"    }  ]; rkresponsedescriptor *buslistresponsedescriptor = [rkresponsedescriptor responsedescriptorwithmapping:buslistmapping                                              method:rkrequestmethodany                                         pathpattern:nil                                             keypath:@"data.tmbs"                                         statuscodes:nil]; [objectmanager addresponsedescriptor:buslistresponsedescriptor]; return yes; 

}

i've created entity model named bus coredata. when check localdatabase in device, there busdb.sqlite, not other 1 !!