I had to do something similar to this. Here's our approach.
We set the project orientation to only support Portrait mode.
Then in your AppDelegate add an instance variable for orientation and conform to the supportedInterfaceOrientationsFor delegate method.
static var orientationLock = UIInterfaceOrientationMask.portrait
func application(_ application: UIApplication, supportedInterfaceOrientationsFor window: UIWindow?) -> UIInterfaceOrientationMask {
return AppDelegate.orientationLock
}
Then when your about to present your landscape view perform the following actions:
AppDelegate.orientationLock = UIInterfaceOrientationMask.landscapeLeft
UIDevice.current.setValue(UIInterfaceOrientation.landscapeLeft.rawValue, forKey: "orientation")
UIViewController.attemptRotationToDeviceOrientation()
And on dismissal,
AppDelegate.orientationLock = UIInterfaceOrientationMask.portrait
UIDevice.current.setValue(UIInterfaceOrientation.portrait.rawValue, forKey: "orientation")
UIViewController.attemptRotationToDeviceOrientation()
Hope this helps!