En mi aplicación de barra de pestañas personalizada, la orientación nunca parece cambiar, incluso si fuerzo a girar la barra de estado. Aquí está mi código en mi AppDelegate:

AppDelegate.h:

    #import <UIKit/UIKit.h>
    #import "MBProgressHUD.h"

    @class exampleViewContoller;
    @class example1ViewController;
    @class example2ViewController;
    @class example3ViewController;
    @class example4ViewController;

    @interface <appname>AppDelegate : NSObject <UIApplicationDelegate, MBProgressHUDDelegate> {
        UIWindow *window;
        UITabBarController *rootController;
        exampleViewContoller *viewController;
        example1ViewController *viewController1;
        example2ViewController *viewController2;
        example3ViewController *viewController3;
        example4ViewController *viewController4;
        NSMutableData *responseData;
        NSMutableArray *tweets;
        MBProgressHUD *HUD;
    }

    @property (nonatomic, retain) IBOutlet UIWindow *window;
    @property (nonatomic, retain) IBOutlet UITabBarController *rootController;
    @property (nonatomic, retain) IBOutlet exampleViewContoller *viewController;
    @property (nonatomic, retain) IBOutlet example1ViewController *viewController1;
    @property (nonatomic, retain) IBOutlet example2ViewController *viewController2;
    @property (nonatomic, retain) IBOutlet example3ViewController *viewController3;
    @property (nonatomic, retain) IBOutlet example4ViewController *viewController4;
    @property (nonatomic, retain) NSMutableArray *tweets;

    @end

AppDelegate.m:

    #import "<appname>AppDelegate.h"
    #import "exampleViewContoller.h"
    #import "example1ViewController.h"
    #import "example2ViewController.h"
    #import "example3ViewController.h"
    #import "example4ViewController.h"
    #import "SBJson.h"
    #define TMP NSTemporaryDirectory()

    @implementation <appname>AppDelegate

    @synthesize window = _window;
    @synthesize rootController;
    @synthesize viewController;
    @synthesize viewController1;
    @synthesize viewController2;
    @synthesize viewController3;
    @synthesize viewController4;
    @synthesize tweets;

    #pragma mark -
    #pragma mark Application lifecycle

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {
        CGFloat width = self.rootController.view.bounds.size.width;
        CGFloat height = self.rootController.view.bounds.size.height;
        UIView *v = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, width, height)];
        UIImage *imageView = [UIImage imageNamed:@"TabBarBackground.png"];
        UIColor *kMainColor = [[UIColor alloc] initWithPatternImage:imageView];

        [v setBackgroundColor:kMainColor];
        [kMainColor release];

        [self.rootController.tabBar insertSubview:v atIndex:0];
        [imageView release];
        [v release];

        responseData = [[NSMutableData data] retain];
        tweets = [NSMutableArray array];
        NSURLRequest *request = [NSURLRequest requestWithURL:
                         [NSURL URLWithString:@"http://api.twitter.com/1/statuses/user_timeline.json?screen_name=ENTER_USER_HERE&count=20"]];
        [[NSURLConnection alloc] initWithRequest:request delegate:self];

        NSAssert(nil != self.rootController, @"tab bar controller not hooked up!");

        BOOL iPad = NO;
#ifdef UI_USER_INTERFACE_IDIOM
        iPad = (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad);
#endif

        if (iPad) {
            self.viewController = [[[exampleViewContoller alloc] initWithNibName:@"exampleViewController_iPad" bundle:nil] autorelease];
            self.viewController1 = [[example1ViewController alloc] initWithNibName:@"example1ViewController_iPad" bundle:nil] autorelease];
            self.viewController2 = [[[example2ViewController alloc] initWithNibName:@"example2ViewController_iPad" bundle:nil] autorelease];
            self.viewController3 = [[[example3ViewController alloc] initWithNibName:@"example3ViewController_iPad" bundle:nil] autorelease];
            self.viewController4 = [[[example4ViewController alloc] initWithNibName:@"example4ViewController_iPad" bundle:nil] autorelease];
        } else {
            self.viewController = [[[exampleViewContoller alloc] initWithNibName:@"exampleViewContoller_iPhone" bundle:nil] autorelease];
            self.viewController1 = [[[example1ViewController alloc] initWithNibName:@"example1ViewController_iPhone" bundle:nil] autorelease];
            self.viewController2 = [[[example2ViewController alloc] initWithNibName:@"example2ViewController2_iPhone" bundle:nil] autorelease];
            self.viewController3 = [[[example3ViewController alloc] initWithNibName:@"example3ViewController_iPhone" bundle:nil] autorelease];
            self.viewController4 = [[[example4ViewController alloc] initWithNibName:@"example4ViewController_iPhone" bundle:nil] autorelease];
        }
            self.rootController.viewControllers = [NSArray arrayWithObjects:self.viewController, self.viewController4, self.viewController1, self.viewController3, self.viewController2, nil];

        [viewController release];
        [viewController1 release];
        [viewController2 release];
        [viewController3 release];
        [viewController4 release];

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_4_0
        self.window.rootViewController = self.rootController;
#else
        [self.window addSubview:rootController.view];
#endif
        [self.window makeKeyAndVisible];
        HUD = [[MBProgressHUD alloc] initWithView:viewController.view];
        [viewController.view addSubview:HUD];
        [HUD show:NO];

        HUD.delegate = self;

        HUD.labelText = @"Loading";


        return YES;
    }

//[---CODE CLIP---]

    - (void)application:(UIApplication *)application didChangeStatusBarOrientation:(UIInterfaceOrientation)oldStatusBarOrientation {
        CGFloat width = self.rootController.view.bounds.size.width*2;
        CGFloat height = self.rootController.view.bounds.size.height;
        UIView *v = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, width, height)];
        UIImage *imageView = [UIImage imageNamed:@"TabBarBackground.png"];
        UIColor *kMainColor = [[UIColor alloc] initWithPatternImage:imageView];

        [v setBackgroundColor:kMainColor];
        [kMainColor release];
        [self.rootController.tabBar insertSubview:v atIndex:0];
        [imageView release];
        [v release];

    }

    - (void)hudWasHidden {
        [HUD removeFromSuperview];
    }

//[---CODE CLIP---]

    - (void)dealloc
    {
        [_window release];
        [rootController release];
        [HUD release];
        [super dealloc];
    }

    @end

El problema es que cuando giro el dispositivo en iOS Simulator, la aplicación no gira. ¡Cualquier idea sería muy apreciada

ACTUALIZA

ambién he notado que la imagen de lanzamiento tampoco está girando (para iPad, es decir, el iPhone no hace imágenes de lanzamiento horizontal).

NOTA PARA JMANS

I anuló UITabBarController:

@implementation UITabBarController (MyApp)

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {
    if(self.selectedIndex==4) 
        return (toInterfaceOrientation == UIInterfaceOrientationPortrait);
    else
        return (toInterfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}
@end