Presented UIViewController refuses to lay out with landscape orientation - ios

Question

I am updating a 5-year-old app (originally written for iOS 3!). I have made decent inroads in using autolayout and addressing deprecation warnings. But the old technique used for presenting a different view controller when the device is rotated no longer works reliably.
- (void)orientationChanged:(NSNotification *)notification {
UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
if (deviceOrientation == UIInterfaceOrientationLandscapeRight && !showingOtherVC) {
// switch to other VC
othervc.modalPresentationStyle = UIModalPresentationOverFullScreen;
[self presentViewController:othervc animated:YES completion:nil];
[self resignFirstResponder];
}
The other view controller does appear, but it's laid out sideways, for a portrait screen, not landscape, even though the device is in a landscape orientation.
How can I update this in a reasonably easy way (i.e., not a rewrite in Swift, not restructuring the app with storyboards — which Xcode doesn't seem to facilitate via copy/paste)? And, for the benefit of others who may happen on this question, what would be the more correct way to achieve this result (new VC on orientation change) if I were writing this from scratch?
Thank you.

Answer 1

This was a really stupid error, but in case someone else makes it and ends up here, this was the problem.
Instead of correctly returning the mask constant:
-(UIInterfaceOrientationMask)supportedInterfaceOrientations {
return (UIInterfaceOrientationMaskLandscapeRight);
}
I was returning this other constant that autocomplete gave me:
-(UIInterfaceOrientationMask)supportedInterfaceOrientations {
return (UIInterfaceOrientationLandscapeRight);
}