What is the "requestGeometryUpdateWithPreferences" invocation "viewWillTransitionToSize:withTransitionCoordinator:" mechanism ?

First.

I call the "requestGeometryUpdateWithPreferences with UIInterfaceOrientationMaskPortrait" at Portrait , its not going to work.

// the phone is Portrait
pIOS.interfaceOrientations = UIInterfaceOrientationMaskPortrait;
[scene requestGeometryUpdateWithPreferences:pIOS errorHandler:^(NSError * _Nonnull error) {}];

// "viewWillTransitionToSize:withTransitionCoordinator:" will not call

Then Next.

I call the "requestGeometryUpdateWithPreferences with UIInterfaceOrientationMaskLandscapeRight" at Portrait. Now it will call "viewWillTransitionToSize:withTransitionCoordinator:" twice.

// the phone is Portrait
pIOS.interfaceOrientations = UIInterfaceOrientationMaskLandscapeRight;
[scene requestGeometryUpdateWithPreferences:pIOS errorHandler:^(NSError * _Nonnull error) {}];

// "viewWillTransitionToSize:withTransitionCoordinator:" will call twice

The Phone manifested as goto LanscapeRight and immediately back to Portrait

Is this a BUG?