Mostrar una vista modal de izquierda a derecha

Para abrir la ventana

CATransition *transition = [CATransition animation];
transition.duration = 0.3;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromRight;
[self.view.window.layer addAnimation:transition forKey:nil];
[self presentModalViewController:viewCtrl animated:NO];

Para cerrar la ventana cambiamos la llamada:

[self presentModalViewController:viewCtrl animated:YES];

Por

CATransition *transition = [CATransition animation];
transition.duration = 0.3;
transition.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
transition.type = kCATransitionPush;
transition.subtype = kCATransitionFromRight;
[self.view.window.layer addAnimation:transition forKey:nil];

[self presentModalViewController:viewCtrl animated:NO];