BackBarButtonItem BackButtonBackgroundVerticalPositionAdjustment

I am trying to set the vertical position of the inverse UIBarButtonItem and has no effect. I don't want to do this as a UIAppearance selector as I just want this to be used in one class. What am I doing wrong?

I've tried this in parent and child view controllers.

[self.navigationItem.backBarButtonItem setBackButtonBackgroundVerticalPositionAdjustment:-10 forBarMetrics:UIBarMetricsDefault];

      

        
        
        
      

    

Thank!