ios - Adding a UIBarButtomItem but it does not showup on interface -

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i trying add go button viewcontroller programatically not show on interface via simulator. missing in code?? there build errors blank screen!

#import "viewcontroller.h"  @interface viewcontroller () @end  @implementation viewcontroller - (void) performadd:(id)paramsender{    nslog(@"button got called"); }  - (void)viewdidload {     [super viewdidload]; // additional setup after loading view, typically nib.      self.view.backgroundcolor = [uicolor blackcolor];     self.title =@"go back";      self.navigationitem.rightbarbuttonitem = [[uibarbuttonitem alloc]      initwithbarbuttonsystemitem:(uibarbuttonsystemitemadd)      target:self      action:@selector(performadd:)]; }  - (void)didreceivememorywarning {     [super didreceivememorywarning];     // dispose of resources can recreated. } @end


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