TF-2871 Add adr for push notification click logic on iOS

docs/adr/0049-view-one-by-one-pdf-in-dart-side-in-only-web-app.md

@@ -1,4 +1,4 @@
-# 48. View one-by-one PDF in Dart side in only Web app
+# 49. View one-by-one PDF in Dart side in only Web app
 
 Date: 2024-05-17
 

docs/adr/0050-android-notification-permission-check.md

@@ -1,4 +1,4 @@
-# 48. Notification setting
+# 50. Android notification permission check
 
 Date: 2024-06-07
 

docs/adr/0051-push-notification-click-logic-on-ios.md

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+# 51. Push notification click logic on iOS
+
+Date: 2024-06-07
+
+## Status
+
+Accepted
+
+## Context
+
+On iOS, we use `Notification Service Extension` [NSE](https://developer.apple.com/documentation/usernotifications/modifying-content-in-newly-delivered-notifications) to modify email content first when displaying push notifications to users.
+- In NSE we have implemented getting `new email list` based on `EmailDeliveryState` sent from FCM.
+- NSE only modifies and displays 1 notification, so we will display the notification for the last email in the list via NSE (is called `RemoteNotification`). 
+For the remaining emails we will use [UNUserNotificationCenter](https://developer.apple.com/documentation/usernotifications/unusernotificationcenter) to automatically display notifications (is called `LocalNotification`).
+
+## Decision
+
+Brief the logic flows when clicking notifications:
+
+1. Foreground/Background state
+
+- When clicking on notifications (both LocalNotification and RemoteNotification) the `didReceive` function of `UNUserNotificationCenter` in `AppDelegate` will be called.
+
+```swift
+ override func userNotificationCenter(
+    _ center: UNUserNotificationCenter, 
+    didReceive response: UNNotificationResponse, 
+    withCompletionHandler completionHandler: @escaping () -> Void
+ ) {}
+```
+
+`response.notification.request.content.userInfo` is the contents of the push payload notification.
+We use `FlutterMethodChannel` to pass `UserInfo` from iOS native code to Flutter dart code
+
+```swift
+  self.notificationInteractionChannel?.invokeMethod("current_email_id_in_notification_click_on_foreground", arguments: response.notification.request.content.userInfo)
+```
+
+2. Terminated state
+
+- With `RemoteNotification`, we will get the push notification payload through `launchOptions?[.remoteNotification]` in the `didFinishLaunchingWithOptions` function of `AppDelegate`
+
+```swift
+override func application(
+    _ application: UIApplication,
+    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
+) -> Bool {}
+```
+
+Save it in a `remoteNotificationPayload` variable in memory and use `FlutterMethodChannel` to retrieve it every time you open the app.
+
+```swift
+self.notificationInteractionChannel?.setMethodCallHandler { (call, result) in
+    switch call.method {
+        case "current_email_id_in_notification_click":
+            result(self.remoteNotificationPayload)
+            self.remoteNotificationPayload = nil
+        default:
+            break
+    }
+}
+```
+
+- As for `LocalNotification`, we will receive the push notification payload at the `didReceive` function of `UNUserNotificationCenter` (similar to `Foreground/Background state`)
+
+```swift
+ override func userNotificationCenter(
+    _ center: UNUserNotificationCenter,
+    didReceive response: UNNotificationResponse,
+    withCompletionHandler completionHandler: @escaping () -> Void
+) {
+    self.remoteNotificationPayload = response.notification.request.content.userInfo
+ }
+```
+
+## Consequences
+
+- The application is correctly adjusted to the detailed screen email when clicking on the notification.
+- Any changes to the click push notification logic must be updated in this ADR.