ios - Why is my NSSet coming up empty? -

i working on app opens tableview, once cell selected user taken second tableview of options related first cell selected in first tableview. on second tableview, user should select 1 more cell , taken detail view.

i have first tableview showing , second tableview displaying should. problem selecting on second tableview , being taken detail view. detail view screen comes up, empty.

i have tried adding nslogs see if nsset contains anything, doesn't seem show anything. have looked sql file , contain data, know has been written in, problem accessing it.

my code prepareforsegue on second tableview screen below. please tell me if see terribly wrong.

- (void)prepareforsegue:(uistoryboardsegue *)segue sender:(id)sender {  if ([segue.identifier isequaltostring:@"toexplanation"]) {       nsindexpath *indexpath = [self.tableview indexpathforselectedrow];     explanationviewcontroller *destviewcontroller = segue.destinationviewcontroller;      nsset *optionchoices = [[self threescreen] theoptions];     _selectioncontent = [optionchoices allobjects];     nslog(@"%@",[optionchoices allobjects]);     nssortdescriptor *namesort = [[nssortdescriptor alloc] initwithkey:@"name" ascending:yes];     nsarray *sortedchoices = [optionchoices sortedarrayusingdescriptors:[nsarray arraywithobject:namesort]];     nslog(@"%@", sortedchoices);       option *option = [sortedchoices objectatindex:indexpath.row];     destviewcontroller.explaintome = option.explanation;     //destviewcontroller.explaintome = @"working?";     nslog(@"%@",option.explanation);  } 

if uncomment 'destviewcontroller.explainttome = @"working?"; can see 'working?' in detailview.