SwiftUI - Determining Current Device and Orientation - ios

Question

I am trying to detect when the device is on iPad and in Portrait.
Currently I use the UIDevice API in UIKit and use an environment object to watch changes. I use the solution found here - Determining Current Device and Orientation.
However the orientationInfo.orientation is initially always equal to .portrait until rotated into portrait and then back to landscape.
So when doing the following to display the FABView
struct HomeView: View {
#EnvironmentObject var orientationInfo: OrientationInfo
let isPhone = UIDevice.current.userInterfaceIdiom == .phone
var body: some View {
ZStack(alignment: .bottom) {
#if os(iOS)
if isPhone == false && orientationInfo.orientation == .portrait {
FABView()
}
#endif
}
}
}
The view is loaded when the iPad is initially in landscape, but when changing to portrait and back to landscape is then removed. Why is this happening and how can I make sure the view isn't loaded on first load ?
Full Code
struct HomeTab: View {
var body: some View {
NavigationView {
HomeView()
.environmentObject(OrientationInfo())
}
}
}
struct HomeView: View {
#EnvironmentObject var orientationInfo: OrientationInfo
let isPhone = UIDevice.current.userInterfaceIdiom == .phone
var body: some View {
ZStack(alignment: .bottom) {
#if os(iOS)
if isPhone == false && orientationInfo.orientation == .portrait {
FABView()
}
#endif
}
}
}
final class OrientationInfo: ObservableObject {
enum Orientation {
case portrait
case landscape
}
#Published var orientation: Orientation
private var _observer: NSObjectProtocol?
init() {
// fairly arbitrary starting value for 'flat' orientations
if UIDevice.current.orientation.isLandscape {
self.orientation = .landscape
}
else {
self.orientation = .portrait
}
// unowned self because we unregister before self becomes invalid
_observer = NotificationCenter.default.addObserver(forName: UIDevice.orientationDidChangeNotification, object: nil, queue: nil) { [unowned self] note in
guard let device = note.object as? UIDevice else {
return
}
if device.orientation.isPortrait {
self.orientation = .portrait
}
else if device.orientation.isLandscape {
self.orientation = .landscape
}
}
}
deinit {
if let observer = _observer {
NotificationCenter.default.removeObserver(observer)
}
}
}

Answer 1

You can use UIDevice.orientationDidChangeNotification for detecting orientation changes but you shouldn't rely on it when the app starts.
UIDevice.current.orientation.isValidInterfaceOrientation will be false at the beginning and therefore both
UIDevice.current.orientation.isLandscape
and
UIDevice.current.orientation.isPortrait
will return false.
Instead you can use interfaceOrientation from the first window scene:
struct ContentView: View {
#State private var isPortrait = false
var body: some View {
Text("isPortrait: \(String(isPortrait))")
.onReceive(NotificationCenter.default.publisher(for: UIDevice.orientationDidChangeNotification)) { _ in
guard let scene = UIApplication.shared.windows.first?.windowScene else { return }
self.isPortrait = scene.interfaceOrientation.isPortrait
}
}
}
Also note that device orientation is not equal to interface orientation. When the device is upside down in portrait mode, device orientation is portrait but interface orientation can be landscape as well.
I think it's better to rely on the interface orientation in your case.

Answer 2

I would like to add another details that can help in some cases:
You can get orientation by rawValue:
UIDevice.current.orientation.rawValue
Portrait = 1
PortraitUpSideDown = 2
LandscapeLeft = 3 (Top of the Device go left)
LandscapeRight = 4 (Top of the Device go right)
What is often forgotten is that there is also a Flat orientation. This can be an issue when you test your app on the physical device.
Flat = 5 (Device is on the back)
Flat = 6 (Device is on the front/screen)
This is important when you use Notification for UIDevice.orientationDidChangeNotification.
Because you will get notification every time user change Flat orientation, but you expected only to get notified when it goes from Portrait to Landscape and vice versa.
Solutions to this problem
You can use .isValidInterfaceOrientation which returns only Portrait and Landscape orientations.
UIDevice.current.orientation.isValidInterfaceOrientation
You can change var only when rawValue is from 1...4
struct ContentView: View {
#State private var isPortrait = false
var body: some View {
Text("isPortrait: \(String(isPortrait))")
.onReceive(NotificationCenter.default.publisher(for: UIDevice.orientationDidChangeNotification)) { _ in
if UIDevice.current.orientation.rawValue <= 4 { // This will run code only on Portrait and Landscape changes
guard let scene = UIApplication.shared.windows.first?.windowScene else { return }
self.isPortrait = scene.interfaceOrientation.isPortrait
}
}
}
}