how to use automasking in iphone sdk

-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) {
        if (toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft || toInterfaceOrientation == UIInterfaceOrientationLandscapeRight) {
            // UIImage *titleImage = [UIImage imageNamed:@"nav-l"];
            // UIImage *joinImage = [UIImage imageNamed:@"join-port"];
            self.navigationController.title = @"news";
            self.navigationController.navigationBar.tintColor = [UIColor clearColor];
            // [self.navigationController.navigationBar setBackgroundImage:titleImage forBarMetrics:UIBarMetricsDefault];
            //  self.navigationController.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"nav-l.png"]];
            [self.navigationController.navigationBar setNeedsDisplay];
            //   navimg.image=titleImage;
            //   joinimg.image=joinImage;
           
        } else {
            //   UIImage *titleImage = [UIImage imageNamed:@"nav-p"];
            //    UIImage *joinImage = [UIImage imageNamed:@"join-land"];
            self.navigationController.navigationBar.tintColor = [UIColor clearColor];
            //    [self.navigationController.navigationBar setBackgroundImage:titleImage forBarMetrics:UIBarMetricsDefault];
            // self.navigationController.view.backgroundColor = [[UIColor alloc] initWithPatternImage:[UIImage imageNamed:@"nav-p.png"]];
            [self.navigationController.navigationBar setNeedsDisplay];
            //   navimg.image=titleImage;
            //   joinimg.image = joinImage;
        }
    }
}