IOS PWA FCM 通知 - onMessage 从不调用，onBackgroundMessage 始终调用

问：

截至目前（11 月 23 日），我正试图弄清楚在 IOS 上的 PWA 中可以做什么和不能做什么。我已经开始测试 FCM 通知，在主页上安装了 PWA，并且我在操作系统中显示了通知 - 这感觉是一个很好的开始。但是，我注意到当应用程序打开时，这些通知不会触发页面上的 onMessage 事件，这意味着我无法在已打开的应用程序中更新显示。我在控制台上看不到任何错误。我还注意到 onBackgroundMessage 始终在 Service Worker 中被调用。代码全部基于 FCM 快速入门示例。

Service Worker 如下所示

// Import and configure the Firebase SDK
// These scripts are made available when the app is served or deployed on Firebase Hosting
// If you do not serve/host your project using Firebase Hosting see https://firebase.google.com/docs/web/setup
importScripts('./firebase-app-compat.js');
importScripts('./firebase-messaging-compat.js');
importScripts('./init.js');

const messaging = firebase.messaging();

// If you would like to customize notifications that are received in the
// background (Web app is closed or not in browser focus) then you should
// implement this optional method.
// Keep in mind that FCM will still show notification messages automatically 
// and you should use data messages for custom notifications.
// For more info see: 
// https://firebase.google.com/docs/cloud-messaging/concept-options
messaging.onBackgroundMessage(function(payload) {
  console.log('[firebase-messaging-sw.js] Received background message ', payload);
  // Customize notification here
  const notificationTitle = 'Background Message Title';
  const notificationOptions = {
    body: 'Background Message body.',
    icon: './firebase-logo.png'
  };

  self.registration.showNotification(notificationTitle,
    notificationOptions);
});

页面上的脚本：

 // Retrieve Firebase Messaging object.
      const messaging = firebase.messaging();
      var reg = null;
      if ("serviceWorker" in navigator) {
        window.addEventListener("load", function () {
          navigator.serviceWorker.register("./firebase-messaging-sw.js").then(
            function (registration) {
              
              console.log(
                "SW registration successful with scope: ",
                registration.scope
              );
            },
            function (err) {
              console.log("SW registration failed: ", err);
            }
          );
        });
        navigator.serviceWorker.ready.then(registration => {
          reg = registration;
          resetUI();
            
          });
      }
      // Handle incoming messages. Called when:
      // - a message is received while the app has focus
      // - the user clicks on an app notification created by a service worker
      //   `messaging.onBackgroundMessage` handler.
      messaging.onMessage((payload) => {
        console.log("Message received. ", payload);
        // Update the UI to include the received message.
        appendMessage(payload);
      });
     function resetUI() {
        console.log("RESET UI");
        clearMessages();
        showToken("loading...");
        // Get registration token. Initially this makes a network call, once retrieved
        // subsequent calls to getToken will return from cache.
        messaging
          .getToken({
            serviceWorkerRegistration:reg,
            vapidKey:
              "[vapidKey]",
          })
          .then((currentToken) => {
            if (currentToken) {
              sendTokenToServer(currentToken);
              updateUIForPushEnabled(currentToken);
            } else {
              // Show permission request.
              console.log(
                "No registration token available. Request permission to generate one."
              );
              // Show permission UI.
              updateUIForPushPermissionRequired();
              setTokenSentToServer(false);
            }
          })
          .catch((err) => {
            console.log("An error occurred while retrieving token. ", err);
            showToken("Error retrieving registration token. ", err);
            setTokenSentToServer(false);
          });
      }

任何指针，这样我就可以在收到推送通知时更新显示，并且仅在应用程序未打开时才显示推送通知，这将很棒。