Ios5 具有容器控制器和UINavigationController的UIViewController层次结构中出现意外UIView偏移

我有一个UINavigationController和许多子视图控制器，其中一些是容器控制器。上次添加的子UIViewController的UIView框架布局（绿色背景）在不应显示的情况下显示其父背景（黄色）

如何布局所有内容，使所有视图都在导航栏下方的屏幕范围内，而不出现奇怪的偏移

UIViewController层次结构，在my AppDelegate中启动：

UINavigationController rootViewController:FrontFacadeViewController < UIViewController
    view (0,0) dim:(320x460)

    => StandardCoverViewController < UIViewController
    added as addSubview of FrontFacadeViewController's view]    
    view: (0,0) dim:(320x460)       

        => ConfigurationViewController < UIViewController
        added by pushing onto self.navigationController
        view: (0,20) (320x460)

            => GearViewController < UIViewController
            added as subview of ConfigurationViewController's view 
            view: (0,0) (320x416)

FrontFacadeViewController：

// FrontFacadeViewController determines a particular view controller to present 
// based on some business logic.
// Because of this, it adds child UIViewControllers using container controllers.
//
- (void)viewDidLoad {
    StandardCoverViewController *controller = [StandardCoverViewController alloc] initWithNibName:nil bundle:self.nibBundle];

    [self addChildViewController:controller];
    [controller didMoveToParentViewController:self];    
    [self.view addSubview:controller.view];    
    [controller didMoveToParentViewController:self];    
}

- (IBAction)onButtonPress {
    ConfigurationViewController *controller = [[ConfigurationViewController alloc] initWithNibName:nil bundle:self.nibBundle];
    [self.navigationController pushViewController:controller animated:YES];        
}   

ConfigurationViewController：（黄色背景）

GearViewController：（绿色背景）

---

我做错了吗？

确实发生在我身上，但我不记得我做了什么来修复它=（如果你记得，那会很有帮助。

// FrontFacadeViewController determines a particular view controller to present 
// based on some business logic.
// Because of this, it adds child UIViewControllers using container controllers.
//
- (void)viewDidLoad {
    StandardCoverViewController *controller = [StandardCoverViewController alloc] initWithNibName:nil bundle:self.nibBundle];

    [self addChildViewController:controller];
    [controller didMoveToParentViewController:self];    
    [self.view addSubview:controller.view];    
    [controller didMoveToParentViewController:self];    
}

- (IBAction)onButtonPress {
    ConfigurationViewController *controller = [[ConfigurationViewController alloc] initWithNibName:nil bundle:self.nibBundle];
    [self.navigationController pushViewController:controller animated:YES];        
}   

- (void)viewDidLoad {
    [self.view setBackgroundColor:[UIColor yellowColor]];
    GearViewController *controller = [[GearViewController alloc] initWithNibName:nil bundle:self.nibBundle];
    [self addChildViewController:controller];
    [self.view addSubview:controller.view];
    [controller didMoveToParentViewController:self];    
}

- (void)viewDidLoad {
    [self.view setBackgroundColor:[UIColor greenColor]];
    // nothing special
}