SwiftUI中如何使用@EnvironmentObject在AppDelegate和SceneDelegate/Views之间共享数据

Question

在 SwiftUI 5.1 中，我想使用 AppDelegate 创建一个 userData 对象。 userData 还将包含 BLE 广告数据，这些数据也将从 AppDelegate 更新。 UI 应该可以使用这些数据来显示这些值。

我在 AppDelegate 中使用

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    private var centralManager : CBCentralManager!
    var userData: UserData!

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        userData = UserData()

        return true
    }

在 SceneDelegate 我想传递给视图使用

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    @EnvironmentObject var userData: UserData

    var window: UIWindow?

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).

        // Use a UIHostingController as window root view controller
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView:
                BeaconList().environmentObject(userData)
            )

            self.window = window
            window.makeKeyAndVisible()
        }
    }

编译工作正常，但运行代码时我得到

线程 1：致命错误：在外部读取 EnvironmentObject 查看.body

如果我删除了

.environmentObject(userData)

我明白了

线程 1：EXC_BAD_INSTRUCTION（代码=EXC_I386_INVOP，子代码=0x0）

本质上，我正在尝试从 AppDelegate 创建和更新 userData 对象，并从 SceneDelegate 显示并在下面查看。

我该如何实现？

Answer 1

也许您可以使用UIApplication.shared.delegate 让 AppDelegate 访问用户数据：

class AppDelegate: UIResponder, UIApplicationDelegate {

    var userData: UserData!

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        userData = UserData()
        return true
    }
}

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).

        let userData = (UIApplication.shared.delegate as! AppDelegate).userData

        // Use a UIHostingController as window root view controller
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: ContentView().environmentObject(userData))
            self.window = window
            window.makeKeyAndVisible()
        }
    }