title: ios switching views not functional
body: <p>I tried a simple app, switching one view to another.
  but i met a problem, it show error of <code>EXC_BAD_ACCESS THREAD 1</code>,</p>
  
  <p>I used zombie to check the error, it shows the error from the first switch method ,not the back method ,here is the switch method, i am not able to find the error.</p>
  
  <pre><code>- (IBAction)YukiBanButtonPress:(id)sender {
      [[[UIApplication sharedApplication] keyWindow] endEditing:YES];
      AboutUs*AboutusController= [[[AboutUs alloc] initWithNibName:@"AboutUs" bundle:nil] autorelease];
      [AboutusController setModalTransitionStyle:UIModalTransitionStyleCoverVertical];
      [self.view addSubview:AboutusController.view];
      [self.navigationController pushViewController:AboutusController animated:YES];
      [AboutusController.view setFrame:self.view.bounds];
      [AboutusController setYukiBan];
      [AboutusController.navigationItem setTitle:@"YUKI BAN"];
  }
  </code></pre>
  
  <p>here is the backbutton program </p>
  
  <pre><code>UINavigationItem*item= [NavigationBar.items objectAtIndex:0];
      UINavigationItem *back = [[UINavigationItem alloc] initWithTitle:@"Back"];
      NSArray *items = [[NSArray alloc] initWithObjects:back,item,nil];
      [NavigationBar setItems:items];
      [back release];
      [items release];
      [NavigationBar setDelegate:self];
  </code></pre>
  
  <p>How can i fix this?</p>