shouldAutorotateToInterfaceOrientation doesn't work properly

Question

I want to lock orientation to Portrait if device is iPhone, and allow all orientations if the device is iPad.

I have this code, but it doesn't lock iPhone in Portrait mode:

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) 
    {
        return NO;

    }
    else
    {
    if (interfaceOrientation == UIInterfaceOrientationPortrait || interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown || interfaceOrientation == UIInterfaceOrientationLandscapeLeft || interfaceOrientation == UIInterfaceOrientationLandscapeRight)
        return YES;
    }
    return NO;

}

What is the problem?

Answer 1

if you will navigate the view then force orientation will not work but if you will     present your view then it will work very well and it works for me. In my project all screens are in portrait mode only but only one screen is in landscape mode.   
- (IBAction)startButtonClicked:(id)sender {

CTFailure_RemedyGameViewController *remedyGameController = [[CTFailure_RemedyGameViewController alloc]initWithNibName:@"CTFailure_RemedyGameViewController" bundle:nil];
[self presentModalViewController:remedyGameController animated:NO];
[remedyGameController release];
}

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

@end

Answer 2

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone) 
    {
        return (interfaceOrientation == UIInterfaceOrientationPortrait || interfaceOrientation == UIInterfaceOrientationPortraitUpsideDown);

    }
    else{
        return YES;
    }

}

Try this. Hope this helps.