SwiftUI Repaint View Components on Device Rotation

Question

How to detect device rotation in SwiftUI and re-draw view components?

I have a @State variable initialized to the value of UIScreen.main.bounds.width when the first

Answer 1

I got

"Fatal error: No ObservableObject of type SomeType found"

because I forgot to call contentView.environmentObject(orientationInfo) in SceneDelegate.swift. Here is my working version:

// OrientationInfo.swift
final class OrientationInfo: ObservableObject {
    @Published var isLandscape = false
}

// SceneDelegate.swift
var orientationInfo = OrientationInfo()

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    // ...
    window.rootViewController = UIHostingController(rootView: contentView.environmentObject(orientationInfo))
    // ...
}

func windowScene(_ windowScene: UIWindowScene, didUpdate previousCoordinateSpace: UICoordinateSpace, interfaceOrientation previousInterfaceOrientation: UIInterfaceOrientation, traitCollection previousTraitCollection: UITraitCollection) {
    orientationInfo.isLandscape = windowScene.interfaceOrientation.isLandscape
}

// YourView.swift
@EnvironmentObject var orientationInfo: OrientationInfo

var body: some View {
    Group {
        if orientationInfo.isLandscape {
            Text("LANDSCAPE")
        } else {
            Text("PORTRAIT")
        }
    }
}