Merge pull request #1050 from OneSignal/fix/ios_declined_notification-permission-change

[Fix] iOS denied notificationPermissionChange

Author: jkasten2

src/managers/SubscriptionManager.ts

@@ -334,15 +334,12 @@ export class SubscriptionManager {
       const permission = await SubscriptionManager.requestPresubscribeNotificationPermission();
 
       /*
-        Notification permission changes are already broadcast by the page's
-        notificationpermissionchange handler. This means that allowing or
-        denying the permission prompt will cause double events. However, the
-        native event handler does not broadcast an event for dismissing the
+        The native event handler does not broadcast an event for dismissing the
         prompt, because going from "default" permissions to "default"
         permissions isn't a change. We specifically broadcast "default" to "default" changes.
        */
-      if (permission === NotificationPermission.Default)
-        await PermissionUtils.triggerNotificationPermissionChanged(true);
+      const forcePermissionChangeEvent = permission === NotificationPermission.Default
+      await PermissionUtils.triggerNotificationPermissionChanged(forcePermissionChangeEvent);
 
       // If the user did not grant push permissions, throw and exit
       switch (permission) {

src/utils/PermissionUtils.ts

@@ -2,7 +2,20 @@ import Database from "../services/Database";
 import Event from '../Event';
 
 export class PermissionUtils {
+
+  // This flag prevents firing the NATIVE_PROMPT_PERMISSIONCHANGED event twice
+  // We use multiple APIs:
+  //    1. Notification.requestPermission callback
+  //    2. navigator.permissions.query({ name: 'notifications' }`).onchange
+  // Some browsers support both, while others only support Notification.requestPermission
+  private static executing = false;
+
   public static async triggerNotificationPermissionChanged(updateIfIdentical = false) {
+    if (PermissionUtils.executing) {
+      return;
+    }
+    PermissionUtils.executing = true;
+
     const newPermission = await OneSignal.privateGetNotificationPermission();
     const previousPermission = await Database.get('Options', 'notificationPermission');
 
@@ -13,5 +26,6 @@ export class PermissionUtils {
 
     await Database.put('Options', { key: 'notificationPermission', value: newPermission });
     Event.trigger(OneSignal.EVENTS.NATIVE_PROMPT_PERMISSIONCHANGED, { to: newPermission });
+    PermissionUtils.executing = false;
   }
 }