[Bug] [iOS] App delegate swizzler has no UIScene equivalent — cold-launch & universal links miss Analytics/Dynamic Links on scene-based apps

Bắt đầu từ app/src/invites/ios/invites_ios_startup.mm, đọc RunOnAppDelegateClasses và HookAppDelegateMethods cùng với các hook UIApplicationDelegate được liệt kê. Theo dõi các đường dẫn phân phối của scene delegate được mô tả trong issue và xác định cách coverage có thể đến được Dynamic Links và Analytics trong khi vẫn giữ nguyên implementation ban đầu; hoàn thành khi các đường dẫn URL và user-activity được báo cáo của cold-launch và scene đã kết nối không còn bị âm thầm loại bỏ.

Environment

• Platform: iOS (scene-based lifecycle, UIWindowSceneDelegate)
• Firebase C++ SDK version: (also consumed via Firebase Unity SDK 12.10.1)
• Installed via: Unity (FirebaseCppApp / FirebaseCppAnalytics), with FirebaseAnalytics/FirebaseCore pods 11.14.0, GoogleUtilities 8.1.2
• Relevant products: Analytics (campaign attribution)

Problem Description

The C++ SDK's iOS app-delegate swizzler (app/src/invites/ios/invites_ios_startup.mm, hooking installed via +load → RunOnAppDelegateClasses → HookAppDelegateMethods) only replaces UIApplicationDelegate methods:

• application:openURL:options:
• application:openURL:sourceApplication:annotation:
• application:continueUserActivity:restorationHandler:
• applicationDidBecomeActive:

There is no UISceneDelegate/UIWIndowSceneDelegate handling anywhere in the C++ SDK (looking at unity-v12.10.1 and v13.10.0)

On modern scene-based apps (UIWindowSceneDelegate), URL/NSUserActivity delivery moves off the app delegate onto the scene delegate. The C++ SDK adds nothing on top. As a result these link-delivery paths reach neither the C++ Dynamic Links machinery nor Analytics:

• scene:willConnectToSession:options: — cold-launch deep links (connectionOptions.URLContexts) and cold-launch universal links (connectionOptions.userActivities)
• scene:openURLContexts: — deep links delivered while the scene is already connected
• scene:continueUserActivity: — universal links delivered while the scene is already connected

Impact: on scene-based iOS apps, cold-launch deep/universal links and connected-scene universal links are silently dropped by the SDK.

Steps to reproduce:

1. Scene-based iOS app (Unity export uses UnityScene : UIWindowSceneDelegate in their latest Editor versions).
2. Register a Dynamic Link / campaign URL.
3. Cold-launch the app via a universal link → delivered to scene:willConnectToSession:options:.
4. Observe: no firebase::/GUL frame in the stack for that delivery; no Dynamic Link resolution; no Analytics campaign event. (Same for scene:continueUserActivity: or scene:openURLContexts: while connected.)

Question for maintainers:

• Is scene-delegate support planned for the C++ SDK's swizzler?

Workaround we're using (and would like validated):

We swizzle only the three uncovered scene methods on the scene delegate and forward to [FIRAnalytics handleOpenURL:] / [FIRAnalytics handleUserActivity:], chaining to the original implementation so the engine's own deep-link handling is preserved. Is this the recommended approach, and is there any double-handling risk if the SDK later completes scene coverage?