Forcing portrait orientation for a view controller is not working

Question

My app supports all interface orientations, but I want a certain view to be shown only in portrait. I have this implementation of an UINavigationController subclass:

@implementation CustomNavigationController

- (BOOL)shouldAutorotate
{
   return [[self.viewControllers lastObject] shouldAutorotate];
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations
{
   return [[self.viewControllers lastObject] supportedInterfaceOrientations];
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
   return [[self.viewControllers lastObject] preferredInterfaceOrientationForPresentation];
}

// More methods

@end

Then, for its root view controller, I have implemented:

- (void)viewWillAppear:(BOOL)animated
{
   [super viewWillAppear:animated];

   NSNumber *value = [NSNumber numberWithInt:UIInterfaceOrientationPortrait];
   [[UIDevice currentDevice] setValue:value forKey:@"orientation"];
}

- (BOOL)shouldAutorotate
{
    return YES;
}

- (UIInterfaceOrientationMask)supportedInterfaceOrientations
{
   return UIInterfaceOrientationMaskPortrait;
}

- (UIInterfaceOrientation)preferredInterfaceOrientationForPresentation
{
   return UIInterfaceOrientationPortrait;
}

This prevents the view of the view controller from being rotated to landscape when it is in portrait, but when I navigate to this view being the device already in landscape, and I have been previously in a view which do rotates to landscape, I see this view in landscape as well.

How could I solve this scenario?