如何解决SwiftUI:从AppDelegate内部的函数更改ContentView中的变量
所以我在AppDelegate中有一个用于推送通知功能的寄存器。
@UIApplicationMain
class AppDelegate: UIResponder,UIApplicationDelegate {
var toggler: Toggler?
func application(_ application: UIApplication,didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
return true
}
// MARK: UISceneSession Lifecycle
func application(_ application: UIApplication,configurationForConnecting connectingSceneSession: UISceneSession,options: UIScene.ConnectionOptions) -> UISceneConfiguration {
// Called when a new scene session is being created.
// Use this method to select a configuration to create the new scene with.
return UISceneConfiguration(name: "Default Configuration",sessionRole: connectingSceneSession.role)
}
func application(_ application: UIApplication,didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
// Called when the user discards a scene session.
// If any sessions were discarded while the application was not running,this will be called shortly after application:didFinishLaunchingWithOptions.
// Use this method to release any resources that were specific to the discarded scenes,as they will not return.
}
}
在ContentView中,我有一个想要用于打开和关闭授权的开关。话虽如此,ContentView中的切换是一个@State变量,我认为应该通过registerForPushNotifications()函数设置其值。
struct ContentView: View {
@EnvironmentObject var toggler: Toggler
var body: some View {
VStack {
Toggle(isOn: toggler.$toggleOn) {
Text("Toggle Label")
}
}
}
}
场景代表如下:
class SceneDelegate: UIResponder,UIWindowSceneDelegate {
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).
// Create the SwiftUI view that provides the window contents.
let toggler = Toggler()
if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
appDelegate.toggler = toggler
}
let contentView = ContentView().environmentObject(toggler)
// Use a UIHostingController as window root view controller.
if let windowScene = scene as? UIWindowScene {
let window = UIWindow(windowScene: windowScene)
window.rootViewController = UIHostingController(rootView: contentView)
self.window = window
window.makeKeyAndVisible()
}
}
func sceneDidDisconnect(_ scene: UIScene) {
// Called as the scene is being released by the system.
// This occurs shortly after the scene enters the background,or when its session is discarded.
// Release any resources associated with this scene that can be re-created the next time the scene connects.
// The scene may re-connect later,as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
}
func sceneDidBecomeActive(_ scene: UIScene) {
// Called when the scene has moved from an inactive state to an active state.
// Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
}
func sceneWillResignActive(_ scene: UIScene) {
// Called when the scene will move from an active state to an inactive state.
// This may occur due to temporary interruptions (ex. an incoming phone call).
}
func sceneWillEnterForeground(_ scene: UIScene) {
// Called as the scene transitions from the background to the foreground.
// Use this method to undo the changes made on entering the background.
}
func sceneDidEnterBackground(_ scene: UIScene) {
// Called as the scene transitions from the foreground to the background.
// Use this method to save data,release shared resources,and store enough scene-specific state information
// to restore the scene back to its current state.
}
}
Toggle看起来像:
class Toggler: NSObject,ObservableObject {
@State var toggleOn: Bool = false
}
解决方法
这是要完成的代码,您所做的其他所有更改
class Toggler: ObservableObject {
@Published var toggleOn: Bool = false
}
struct ContentView: View {
@EnvironmentObject var toggler: Toggler
var body: some View {
VStack {
Toggle(isOn: self.$toggler.toggleOn) { // << binding via EnvironmentObject
Text("Toggle Label")
}
}
}
}
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