ios [nfc]: Cut notifications library out of handling "initial notification"

And handle it ourselves, through our dedicated iOS native module
ZLPNotificationsStatus.

(The "initial notification" is a notification that, by being tapped,
launched the app from cold. PR #5676 was about notifications that
are tapped when the app is already open, and that PR fixed a known
bug.)

This, like #5676, makes our iOS notification handling more
transparent. My hope is to smooth the path to custom iOS
notification code in zulip-flutter (zulip-flutter#122, etc.) by
demonstrating a working implementation that's simple and avoids
depending on the details of
@react-native-community/push-notification-ios.

Cutting the library out of this codepath makes one small difference
in the payload we pass to `fromAPNs` on the JS side: the `aps`
property is now present. (So, remove a comment saying it might be
absent). We've never looked at that property, so this is NFC. Unlike
in 2ae6f79 / #5676, there wasn't a call to the library's custom
RCTConvert extensions to account for, as we did there with a
cautious call to RCTJSONClean.

Author: chrisbobbe

ios/ZulipMobile/ZLPNotifications.swift

@@ -45,6 +45,30 @@ class ZLPNotificationsEvents: RCTEventEmitter {
 
 @objc(ZLPNotificationsStatus)
 class ZLPNotificationsStatus: NSObject {
+  // For why we include this, see
+  //   https://reactnative.dev/docs/0.68/native-modules-ios#exporting-constants
+  @objc
+  static func requiresMainQueueSetup() -> Bool {
+    // From the RN doc linked above:
+    // > If your module does not require access to UIKit, then you should
+    // > respond to `+ requiresMainQueueSetup` with NO.
+    //
+    // The launchOptions dictionary (used in `constantsToExport`) is
+    // accessed via the UIApplicationDelegate protocol, which is part of
+    // UIKit:
+    //   https://developer.apple.com/documentation/uikit/uiapplicationdelegate/1622921-application?language=objc
+    //
+    // So I think to follow RN's advice about accessing UIKit, it's probably
+    // right to return `true`.
+    return true
+  }
+
+  // The bridge object, provided by RN's RCTBridgeModule (via
+  // RCT_EXTERN_MODULE in ZLPNotificationsBridge.m):
+  //   https://github.com/facebook/react-native/blob/v0.68.7/React/Base/RCTBridgeModule.h#L152-L159
+  @objc
+  var bridge: RCTBridge!
+
   /// Whether the app can receive remote notifications.
   // Ideally we could subscribe to changes in this value, but there
   // doesn't seem to be an API for that. The caller can poll, e.g., by
@@ -60,4 +84,29 @@ class ZLPNotificationsStatus: NSObject {
         resolve(settings.authorizationStatus == UNAuthorizationStatus.authorized)
       })
   }
+
+  @objc
+  func constantsToExport() -> [String: Any]! {
+    var result: [String: Any] = [:]
+
+    // `launchOptions` comes via our AppDelegate's
+    // `application:didFinishLaunchingWithOptions:` method override. From
+    // the doc for that method (on UIApplicationDelegate):
+    //   https://developer.apple.com/documentation/uikit/uiapplicationdelegate/1622921-application?language=objc
+    // > A dictionary indicating the reason the app was launched (if any).
+    // > The contents of this dictionary may be empty in situations where
+    // > the user launched the app directly. […]
+    //
+    // In particular, for our purpose here: if the app was launched from a
+    // notification, then it wasn't "launched […] directly".
+    //
+    // Empirically, launchOptions *itself* may be missing, which is
+    // different from being empty; the distinction matters in Swift-land
+    // where it's an error to access properties of nil. This doesn't seem
+    // quite covered by "[t]he contents of this dictionary may be empty",
+    // but anyway it explains our optional chaining on .launchOptions.
+    result["initialNotification"] = bridge.launchOptions?[UIApplication.LaunchOptionsKey.remoteNotification] ?? kCFNull
+
+    return result
+  }
 }

src/notification/extract.js

@@ -38,12 +38,6 @@ export const fromAPNsImpl = (data: ?JSONableDict): Notification | void => {
   //
   // For the format this parses, see `ApnsPayload` in src/api/notificationTypes.js .
   //
-  // Though in one case what it actually receives is more like this:
-  //   $Rest<ApnsPayload, {| aps: mixed |}>
-  // That case is the "initial notification", a notification that launched
-  // the app by being tapped, because the `PushNotificationIOS` library
-  // parses the `ApnsPayload` and gives us (through `getData`) everything
-  // but the `aps` property.
 
   /** Helper function: fail. */
   const err = (style: string) =>

src/notification/notifOpen.js

@@ -4,7 +4,6 @@
  * @flow strict-local
  */
 import { NativeModules, Platform } from 'react-native';
-import PushNotificationIOS from '@react-native-community/push-notification-ios';
 
 import type { Notification } from './types';
 import type {
@@ -18,7 +17,7 @@ import type {
 } from '../types';
 import { topicNarrow, pm1to1NarrowFromUser, pmNarrowFromRecipients } from '../utils/narrow';
 import * as logging from '../utils/logging';
-import { fromPushNotificationIOS } from './extract';
+import { fromAPNs } from './extract';
 import { isUrlOnRealm, tryParseUrl } from '../utils/url';
 import { pmKeyRecipientsFromIds } from '../utils/recipient';
 import { makeUserId } from '../api/idTypes';
@@ -29,6 +28,7 @@ import { doNarrow } from '../message/messagesActions';
 import { accountSwitch } from '../account/accountActions';
 import { getIsActiveAccount, tryGetActiveAccountState } from '../account/accountsSelectors';
 import { identityOfAccount } from '../account/accountMisc';
+import type { JSONableDict } from '../utils/jsonable';
 
 /**
  * Identify the account the notification is for, if possible.
@@ -192,13 +192,13 @@ const readInitialNotification = async (): Promise<Notification | null> => {
     const { Notifications } = NativeModules;
     return Notifications.readInitialNotification();
   }
-
-  const notification: ?PushNotificationIOS = await PushNotificationIOS.getInitialNotification();
+  const { ZLPNotificationsStatus } = NativeModules;
+  const notification: JSONableDict | null = ZLPNotificationsStatus.initialNotification;
   if (!notification) {
     return null;
   }
 
-  return fromPushNotificationIOS(notification) || null;
+  return fromAPNs(notification) || null;
 };
 
 export const narrowToNotification =