Cannot catch orientation changes from "upsidedown" to landscapes on iOS - ios

Question

I need to invalidate my collection view layout when screen orientation changes. Since iPhone X and others have safe area insets; I need my cells' subviews positioned according to screen safe area insets.
If you switch between left-right landscapes from portrait there is no problem. But if you switch from upsidedown I cannot catch the orientation change and automatically cannot
I tried two existing approaches.
First is using NotificationCenter. Second is overriding viewWillTransitionToSize:withTransitionCoordinator: function. It's all the same.
in CollectionViewController:
NotificationCenter.default.addObserver(forName: UIDevice.orientationDidChangeNotification, object: nil, queue: nil) { (notif) in
self.collectionViewLayout.invalidateLayout()
}
in Cell:
override func layoutSubviews() {
super.layoutSubviews()
let orientation = UIDevice.current.orientation
if let insets = UIApplication.shared.keyWindow?.safeAreaInsets {
if orientation == .landscapeLeft {
titleLabelLeadingConstraint.constant = insets.left + 20
titleLabelTrailingConstraint.constant = 20
} else if orientation == .landscapeRight {
titleLabelLeadingConstraint.constant = 20
titleLabelTrailingConstraint.constant = insets.right + 20
} else {
titleLabelLeadingConstraint.constant = 20
titleLabelTrailingConstraint.constant = 20
}
}
print("orin: \(orientation.rawValue) | left: \(titleLabelLeadingConstraint.constant) | right: \(titleLabelTrailingConstraint.constant)")
}
The print() function not being called when you switch from/to upsidedown. But collectionviewlayouts invalidateLayout() function is being called.

Answer 1

As you've already tried, you can detect orientation change using viewWillTransitionToSize:withTransitionCoordinator:.
I don't know your first attempt, however, try this:
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
//If you need to invalidate your collectionView layout, do it in this function
super.viewWillTransition(to: size, with: coordinator)
if UIDevice.current.orientation.isLandscape {
//
} else {
//
}
}
If you need to know the difference between landscapeLeft or Right, try your code in this way:
override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
//If you need to invalidate your collectionView layout, do it in this function
super.viewWillTransition(to: size, with: coordinator)
if let insets = UIApplication.shared.keyWindow?.safeAreaInsets {
if UIDevice.current.orientation == .landscapeLeft {
titleLabelLeadingConstraint.constant = insets.left + 20
titleLabelTrailingConstraint.constant = 20
} else if UIDevice.current.orientation == .landscapeRight {
titleLabelLeadingConstraint.constant = 20
titleLabelTrailingConstraint.constant = insets.right + 20
} else {
titleLabelLeadingConstraint.constant = 20
titleLabelTrailingConstraint.constant = 20
}
}
}
NOTE: You don't need to register an observer

Answer 2

OK. At last, I came up with the thing I did not want to do. Observed orientation changes from the cells' themselves.
override func awakeFromNib() {
super.awakeFromNib()
NotificationCenter.default.addObserver(forName: UIDevice.orientationDidChangeNotification, object: nil, queue: nil) { (notif ) in
// doing my things already stated in the question's itself.
}
}
Now they can observe all the changes. But I do not know if this much registration is a wise thing; even though collection view reuses cells and -in my case- 7 to 8 cells are on screen at most.