Allow landscape mode in specific ViewControllers

AppDelegate.m

/* Allow Landscape mode for specific ViewControllers */
-(UIInterfaceOrientationMask)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
    UIViewController* topVC = [self topViewControllerWith: self.window.rootViewController];
    if ([topVC respondsToSelector:@selector(canRotate)]) {
        return UIInterfaceOrientationMaskAllButUpsideDown;
    }
    return UIInterfaceOrientationMaskPortrait;
}

/* get the top ViewController */
- (UIViewController*) topViewControllerWith:(UIViewController *)rootViewController {
    if (rootViewController == nil) { return nil; }
    if ([rootViewController isKindOfClass: [UITabBarController class]]) {
        return [self topViewControllerWith: ((UITabBarController*) rootViewController).selectedViewController];
    }
    else if ([rootViewController isKindOfClass: [UINavigationController class]]) {
        return [self topViewControllerWith: ((UINavigationController*) rootViewController).visibleViewController];
    }
    else if (rootViewController.presentedViewController != nil) {
        return [self topViewControllerWith: [rootViewController presentedViewController]];
    }
    return rootViewController;
}