iphone - Detecting rotation to landscape manually

Question

I am working on an iPhone application based on UITabBarController and UIViewControllers for each page. The app needs to run in portrait mode only, so every view controller + app delegate goes with this line of code:

- (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation {
 return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

There is one view controller where I would like to pop up a UIImageView when the iPhone is rotaed to landscapeleft. The design of the image looks landscape, although the width and height are 320x460 ( so its portrait ).

How can/should I detect this type of rotation manually, just in this specific view controller, withouth having an auto rotation on the entire view?

Thomas

UPDATE:

Thanks!

I added this listener in the viewDidLoad:

 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didRotate:)name:UIDeviceOrientationDidChangeNotification object:nil];

the didRotate looks like this:

- (void) didRotate:(NSNotification *)notification

    {   
        UIDeviceOrientation orientation = [[UIDevice currentDevice] orientation];

        if (orientation == UIDeviceOrientationLandscapeLeft)
        {
            //your code here

        }
    }

Answer 1

I needed that in an old project - hope it still works...

1) Register a notification:

[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(detectOrientation)
                                             name:UIDeviceOrientationDidChangeNotification
                                           object:nil]; 

2) Then you can test against the rotation on change:

-(void) detectOrientation {
    if (([[UIDevice currentDevice] orientation] == UIDeviceOrientationLandscapeLeft) || 
        ([[UIDevice currentDevice] orientation] == UIDeviceOrientationLandscapeRight)) {
        [self doLandscapeThings];
    } else if ([[UIDevice currentDevice] orientation] == UIDeviceOrientationPortrait || [[UIDevice currentDevice] orientation] == UIDeviceOrientationPortraitUpsideDown) {
        [self doPortraitThings];
    }   
}

Hope that helps!