ios - Core Data NSFetchResultController batch size -

nsfetchresultcontroller nsfetchrequest fetchbatchsize = 20 return entities. can be? didn't use sectionkeypath , tried different sort descriptors, it's still return objects.

thanks replies!i explain details. have entity 2 fields - distance , time. have created nsfetchresultcontroller:

func noticesfetcher() -> nsfetchedresultscontroller {      let fetchrequest = nsfetchrequest()      let defaultstore = rkmanagedobjectstore.defaultstore()      let entity = nsentitydescription.entityforname("notice", inmanagedobjectcontext: defaultstore.mainqueuemanagedobjectcontext)     fetchrequest.entity = entity      let distancesortdescriptor = nssortdescriptor(key: "distance", ascending: true)     let timesortdescriptor = nssortdescriptor(key: "time", ascending: false)     let sortdescriptors = [distancesortdescriptor, timesortdescriptor]     fetchrequest.sortdescriptors = sortdescriptors      fetchrequest.fetchbatchsize = 20      let resultfetcher = nsfetchedresultscontroller(fetchrequest: fetchrequest, managedobjectcontext: defaultstore.mainqueuemanagedobjectcontext, sectionnamekeypath: nil, cachename: nil)      return resultfetcher } 

but when perform fetcher have entities in database.(100)

func performfetcher(fetcher: nsfetchedresultscontroller?, filter: nspredicate?, success: (() -> ())?, failure: ((nserror) -> (nserror))?) -> bool {      nsfetchedresultscontroller.deletecachewithname(nil)      var resultperform = false      fetcher?.fetchrequest.predicate = filter      {         try fetcher?.performfetch()         resultperform = true         if success != nil {             success!();         }     }     catch let error nserror {         if failure != nil {             failure!(error)         }     }      return resultperform } 

what can be? result want pagination getter. know can through limit , offset, problem here? thanks

well, depends on mean "return entities." doubt returns array populated entities realized.

the batch size fetch (in case) 20 entities @ time. go ahead , @ set of registered objects moc , can verify happening.

you can fire instruments , watch individual core data fetches take place.

no, batch size fetch not "only 20 entities", fetches entities. can make test project , test batch size?i'm sure have same issue – serd

@serd, answer providers here you, , wrong. if doubt answer, you should create test case demonstrates whether or not correct. why in world should take time so, when 1 problem, , ones freely offering assistance?

if doubt answer, you work, , if find answer in error, provide either correction or evidence answer incorrect.

however, new here, , in hopes may learn experience, i'll provide brief demonstration.

setup moc test adding num_objects instances database.

nsuinteger const num_objects = 1000; nsuinteger const init_batch_size = 100;  - (void)setup {     [super setup];     helper = [[testhelper alloc] init];     url = [[[nsurl fileurlwithpath:nstemporarydirectory()] urlbyappendingpathcomponent:[[nsuuid uuid] uuidstring]] urlbyappendingpathcomponent:@"foo.sqlite"];     [[nsfilemanager defaultmanager] createdirectoryaturl:[url urlbydeletinglastpathcomponent] withintermediatedirectories:yes attributes:nil error:null];     @autoreleasepool {         nsentitydescription *noticeentity = [[nsentitydescription alloc] init];         noticeentity.name = @"notice";         nsattributedescription *distance = [[nsattributedescription alloc] init];         distance.name = @"distance";         distance.attributetype = nsdoubleattributetype;         nsattributedescription *time = [[nsattributedescription alloc] init];         time.name = @"time";         time.attributetype = nsdoubleattributetype;         noticeentity.properties = @[distance, time];         nsmanagedobjectmodel *model = [[nsmanagedobjectmodel alloc] init];         model.entities = @[noticeentity];          nspersistentstorecoordinator *psc = [[nspersistentstorecoordinator alloc] initwithmanagedobjectmodel:model];         [psc addpersistentstorewithtype:nssqlitestoretype configuration:nil url:url options:nil error:null];         moc = [[nsmanagedobjectcontext alloc] initwithconcurrencytype:nsmainqueueconcurrencytype];         moc.persistentstorecoordinator = psc;         (nsuinteger count = 0; count < num_objects; ) {             @autoreleasepool {                 (nsuinteger batchcount = 0; batchcount < init_batch_size && count < num_objects; ++batchcount, ++count) {                     nsmanagedobject *notice = [nsentitydescription insertnewobjectforentityforname:@"notice" inmanagedobjectcontext:moc];                     double distance = ((double)arc4random_uniform(100000)) / (arc4random_uniform(100)+1);                     double time = distance / (arc4random_uniform(100)+1);                     [notice setvalue:@(distance) forkey:@"distance"];                     [notice setvalue:@(time) forkey:@"time"];                 }                 [moc save:null];                 [moc reset];             }         }         [moc save:null];         [moc reset];     } } 

cleanup after test...

- (void)teardown {     [super teardown];     [[nsfilemanager defaultmanager] removeitematurl:[url urlbydeletinglastpathcomponent] error:null]; } 

a couple of helper methods...

- (nsarray*)executefetchwithbatchsize:(nsuinteger)batchsize {     nsfetchrequest *fetchrequest = [nsfetchrequest fetchrequestwithentityname:@"notice"];     fetchrequest.sortdescriptors = @[[nssortdescriptor sortdescriptorwithkey:@"distance" ascending:yes],                                      [nssortdescriptor sortdescriptorwithkey:@"time" ascending:no]];     fetchrequest.fetchbatchsize = batchsize;     return [moc executefetchrequest:fetchrequest error:null]; }  - (nsuinteger)numberoffaults {     nsuinteger numfaults = 0;     (nsmanagedobject *object in moc.registeredobjects) {         if (object.isfault) ++numfaults;     }     return numfaults; } 

a test using default batch size

- (void)testthatfetchrequestwitdefaultbatchsizefetcheseverything {     xctassertequal(0, moc.registeredobjects.count);      nsarray *fetched = [self executefetchwithbatchsize:0];      xctassertequal(num_objects, moc.registeredobjects.count);     xctassertequal(num_objects, fetched.count);     xctassertequal(num_objects, [self numberoffaults]);      [[fetched objectatindex:1] valueforkey:@"distance"];     xctassertequal(num_objects, moc.registeredobjects.count);     xctassertequal(num_objects, fetched.count);     xctassertequal(num_objects-1, [self numberoffaults]); } 

a test using non-default batch size

- (void)testthatfetchrequestwithexplicitbatchsizeonlyfetchesthenumberrequested {     xctassertequal(0, moc.registeredobjects.count);      nsuinteger const batch_size = 20;     nsarray *fetched = [self executefetchwithbatchsize:batch_size];      xctassertequal(0, moc.registeredobjects.count);     xctassertequal(num_objects, fetched.count);     xctassertequal(0, [self numberoffaults]);      [[fetched objectatindex:1] valueforkey:@"distance"];     xctassertequal(batch_size, moc.registeredobjects.count);     xctassertequal(num_objects, fetched.count);     xctassertequal(batch_size-1, [self numberoffaults]); } 

thanks code! have problem nsfetchresultcontroller , nsfetchrequest, have batch size(it's fetches entities – serd

habits die hard. instead of making assertion, should have taken code gave , modified test fetched results controller, , confirm assertion "it's fetches entities" not true. example...

modify helpers tad...

- (nsfetchrequest*)fetchrequestwithbatchsize:(nsuinteger)batchsize {     nsfetchrequest *fetchrequest = [nsfetchrequest fetchrequestwithentityname:@"notice"];     fetchrequest.sortdescriptors = @[[nssortdescriptor sortdescriptorwithkey:@"distance" ascending:yes],                                      [nssortdescriptor sortdescriptorwithkey:@"time" ascending:no]];     fetchrequest.fetchbatchsize = batchsize;     return fetchrequest; }  - (nsarray*)executefetchwithbatchsize:(nsuinteger)batchsize {     return [moc executefetchrequest:[self fetchrequestwithbatchsize:batchsize] error:null]; }  - (nsfetchedresultscontroller*)executefetchusingfetchedresultscontrollerwithbatchsize:(nsuinteger)batchsize {     nsfetchedresultscontroller *frc = [[nsfetchedresultscontroller alloc] initwithfetchrequest:[self fetchrequestwithbatchsize:batchsize] managedobjectcontext:moc sectionnamekeypath:nil cachename:nil];     [frc performfetch:null];     return frc; } 

and change existing tests add tests frc.

- (void)testthatfetchrequestwitdefaultbatchsizefetcheseverythingevenwithfetchedresultscontroller {     xctassertequal(0, moc.registeredobjects.count);      nsfetchedresultscontroller *frc = [self executefetchusingfetchedresultscontrollerwithbatchsize:0];      xctassertequal(num_objects, moc.registeredobjects.count);     xctassertequal(num_objects, frc.fetchedobjects.count);     xctassertequal(num_objects, [self numberoffaults]);      [[frc.fetchedobjects objectatindex:1] valueforkey:@"distance"];     xctassertequal(num_objects, moc.registeredobjects.count);     xctassertequal(num_objects, frc.fetchedobjects.count);     xctassertequal(num_objects-1, [self numberoffaults]); }  - (void)testthatfetchrequestwithexplicitbatchsizeonlyfetchesthenumberrequestedevenwithfetchedresultscontroller {     xctassertequal(0, moc.registeredobjects.count);      nsuinteger const batch_size = 20;     nsfetchedresultscontroller *frc = [self executefetchusingfetchedresultscontrollerwithbatchsize:20];     xctassertequal(moc, frc.managedobjectcontext);      xctassertequal(0, moc.registeredobjects.count);     xctassertequal(num_objects, frc.fetchedobjects.count);     xctassertequal(0, [self numberoffaults]);      [[frc.fetchedobjects objectatindex:1] valueforkey:@"distance"];     xctassertequal(batch_size, moc.registeredobjects.count);     xctassertequal(num_objects, frc.fetchedobjects.count);     xctassertequal(batch_size-1, [self numberoffaults]); }