Does UIView's addSubview really retain the view?

I ran into a situation that seems to suggest otherwise. In the following code snippet, if I remove the line: self.navigationController = nav, the root controller's view won't show up, suggesting to me that addSubview might not actually retain the view as otherwise suggested. Any idea?

- (void)applicationDidFinishLaunching:(UIApplication *)application {   
   self.testViewController = [[TestViewController alloc] initWithNibName:@"TestView" bundle:  [NSBundle mainBundle]];

   UINavigationController *nav = [[UINavigationController alloc]  initWithRootViewController:self.testViewController];

   self.navigationController = nav;  //<-- if this line is removed, test view won't show up

   [window addSubview:nav.view];

   [nav release];
}