title: pushViewController doing nothing in multiple tab app?
body: <p>I have a window based iPhone application with multiple tabs and a navigation bar controller which appears on all these tabs. It's a weather/climate app, so I want the user to first choose a city, then be presented with weather info in each tab for that city (they can go back to the city select from any tab using the navigation bar. I followed this guide: <a href="http://www.youtube.com/watch?v=LBnPfAtswgw" rel="nofollow">http://www.youtube.com/watch?v=LBnPfAtswgw</a> but added more tabs with the same settings. 
  So I get the current tab and instantiate the app delegate like this:</p>
  
  <pre><code>- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
  
  NSUInteger currTab;
  AppDelegate_iPhone *delegate = [[UIApplication sharedApplication] delegate];
  currTab = delegate.rootTabController.selectedIndex;
  ...
  </code></pre>
  
  <p>That works fine, returns correct selected tab when called in viewDidAppear. Then my code for pushing to the corresponding view (in this case, UIForecastViewController) like so:</p>
  
  <pre><code>if (currTab == 0) {
      if (self.forecastViewController == nil) {
          UIForecastViewController *chosenCity = [[UIForecastViewController alloc] initWithNibName:@"UIForecastViewController" bundle:nil];
                     // note forecastViewController is a variable, not the class
          self.forecastViewController = chosenCity;
          [chosenCity release];
      }
      forecastViewController.title = [NSString stringWithFormat:@"%@ Forecast",[cityArray objectAtIndex:row]];
      [delegate.navController pushViewController:forecastViewController animated:YES];
  }
  </code></pre>
  
  <p>Everything else works as it should, but the pushViewController does nothing. I've searched fruitlessly for a solution, there are slightly similar examples out there but none using the app delegate or giving me any results. Hopefully I've mentioned everything I should have, any help/advice will be much appreciated! Regards.</p>