ios - using PFQueryTableViewController as detailviewController of UITableView -

i got uitableview 8 textlabel albumname(displaying array),now want use 'selected album name' parse class name(using initwithcoder method),and display corresponding class value should retrived parsetableview rows. did code:

- (void)prepareforsegue:(uistoryboardsegue *)segue sender:(id)sender  { if ([segue.identifier isequaltostring:@"detailalbum"]) {     nsindexpath *indexpath = [tableview indexpathforselectedrow];       myparsetableviewcontroller *detailscreen =segue.destinationviewcontroller;      uitableviewcell *cell = (uitableviewcell *)[tableview cellforrowatindexpath:indexpath];      detailscreen.classname = cell.textlabel.text;        nslog(@"selected label :%@",detailscreen.classname);  } 

}

and in pfquerytableviewcontroller.h

@interface myparsetableviewcontroller : pfquerytableviewcontroller @property (nonatomic,strong) nsstring *classname; @end 

pfquerytableviewcontroller.m

- (id)initwithcoder:(nscoder *)acoder 

{

self = [super initwithcoder:acoder]; if (self) {      self.parseclassname = self.classname;//showing null here      nslog(@"parse class name1%@",self.parseclassname);       self.textkey = @"songtitle";      self.pulltorefreshenabled = yes;      self.paginationenabled = no; } return self; 

}

when run,i this: selected label : xyz <-----getting class name here,then why not passing parse classname parse class name1(null)<--------

query:

* terminating app due uncaught exception 'nsinvalidargumentexception', reason: '* setobjectforkey: object cannot nil (key: classname)' * first throw call stack:

the reason why app crashing because trying insert nil value nsarray or nsdictionary. instead, need insert [nsnull null].

now, nslog(@"parse class name1%@",self.parseclassname); printing self.parseclassname null because self.classname nil

-initwithcoder: first method called, , object hasn't been instantiated yet. means self.classname return nil. retrieve value coded object, need like:

self.parseclassname = [adecoder decodeobjectforkey:@"classname"];