How to allow only single UIViewController to rotate in both Landscape and Portrait direction?

My app is only for iphone device (both iphone 4 and 5) and built to support only ios 6.

My whole app only supports portrait mode. But there is one view called "ChatView" , which i want to support both landscape and portrait modes.

I have set the required device rotations as follows -

I have also tried following code to support rotation in "ChatView" -

-(BOOL)shouldAutorotate
{
    return YES;
}

-(NSUInteger)supportedInterfaceOrientations
{
    return UIInterfaceOrientationMaskLandscape;
}

But it could not rotate that view.

I have searched a lot for this , but could not be able to find the solution for my issue.

And also in "ChatView" there are some objects like buttons, textfields whose frames are set programmaticaly. So i want to know should i have to set frames of all those objects for landscape mode also?

Please help me.

Thanks.....