Temporarily restrict app to specific orientation - ios

Question

I have an app that supports all orientation, but in certain cases I would like to temporarily restrict it to only portrait. It's not a mix of view controllers that need to be only portrait and those that can be any orientation, rather, I would like to disable orientation changes when the user clicks a button on screen, while the view controller stays the same.
When looking for ways to restrict UI orientation of a UIViewController, methods that pop up are supportedInterfaceOrientations() and preferredInterfaceOrientationForPresentation(). Both don't quite work for me:
supportedInterfaceOrientations() runs only once when the view is loaded, so even if I make its return value conditional, it does not run after the condition changes.
my view controllers are presented inside a navigation stack, not modally, so preferredInterfaceOrientationForPresentation() does not run at all.
Is there any way to achieve the effect I'm looking for?

Answer 1

I'm going to assume your view controllers are in a navigation controller. Without the navigation controller, supportedInterfaceOrientations() is called whenever the device is rotated. HOWEVER, when embedded in a navigation controller, the navigation controller decides whether the view controller should rotate. (See examples below)
What do you need to do? Implement supportedInterfaceOrientations() in a custom UINavigationController like so:
override func supportedInterfaceOrientations() -> UIInterfaceOrientationMask {
if self.topViewController is RootViewController {
return .Portrait
} else {
return .All
}
}
This is a duplicate question of this but I didn't see a swift example. For whatever class you want to stay in portrait, just replace RootViewController with the class name.