SwiftUI DeviceOrientationObserver

SwiftUI_DeviceOrientationObserver.swift

import SwiftUI

public final class DeviceOrientationObserver: ObservableObject {
  public init(notificationCenter: NotificationCenter = .default) {
    observation = notificationCenter.addObserver(
      forName: UIDevice.orientationDidChangeNotification,
      object: nil,
      queue: .main,
      using: { [weak self] notification in
        self?.value = (notification.object as? UIDevice)?.orientation ?? .unknown
      }
    )
  }

  @Published public var value: UIDeviceOrientation = .unknown

  private var observation: NSObjectProtocol?
}

public extension UIDeviceOrientation {
  var angle: Angle {
    switch self {
    case .unknown: return .zero
    case .portrait: return .zero
    case .portraitUpsideDown: return .degrees(180)
    case .landscapeLeft: return .degrees(90)
    case .landscapeRight: return .degrees(-90)
    case .faceUp: return .zero
    case .faceDown: return .zero
    @unknown default: return .zero
    }
  }
}

// MARK: - Example usage

struct ContentView: View {
  @ObservedObject var deviceOrientation = DeviceOrientationObserver()

  var body: some View {
    Image(systemName: "arrow.up") // ⬆
      .imageScale(.large)
      .rotationEffect(deviceOrientation.value.angle) // will point up, regardless device orientation
  }
}