Transition between portrait and landscape

Portrait View :
WhatsOnLandscapeController *whatsOnLandscape = [[[WhatsOnLandscapeController alloc] initWithNibName:@"WhatsOnLandscape" bundle:nil]autorelease];

[whatsOnLandscape setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];
[self presentModalViewController:whatsOnLandscape animated:YES];

Landscape View :
[Leave Landscape View]
[self dismissModalViewControllerAnimated:YES];