fix(ios): use topmost view controller for sign-in presentation

[OrkhanAlikhanov]

Problem

Google Sign-In immediately cancels when triggered from a modal screen (e.g., a login/register modal in React Navigation or Expo Router). The GIDSignIn SDK's auth view controller gets dismissed instantly because it's presented on the root view controller while a modal is already covering it.

Root Cause

getPresentingViewController() returns window.rootViewController, which may already be presenting a modal. When GIDSignIn attempts to present its authentication view controller on a view controller that is already presenting something, iOS dismisses the new presentation immediately, resulting in a GIDSignInError.canceled error.

Fix

Traverse the presentation hierarchy to find the topmost presented view controller.

Summary by CodeRabbit

• Bug Fixes
  • Fixed an issue on iOS where authentication dialogs could appear in incorrect positions on the screen.

[coderabbitai]

📝 Walkthrough

Walkthrough

Updated the getPresentingViewController() method to traverse the view controller hierarchy and return the topmost presented UIViewController instead of just the window's root view controller, with additional safety checks for scene and window availability.

Changes

Cohort / File(s)	Summary
View Controller Retrieval ios/GoogleAuth.swift	Modified getPresentingViewController() to iterate through presented view controllers to find the topmost one in the hierarchy, replacing the previous approach of returning only the root view controller. Added guard statements to validate UIWindowScene and key window existence.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 Hops up the controller tree so tall,
Finding the topmost view of all,
No longer stuck at the root below,
Now reaching where the presents go! 🌳✨

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: finding and using the topmost view controller for sign-in presentation instead of just the root view controller.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@ios/GoogleAuth.swift`:
- Around line 438-449: Replace the use of
UIApplication.shared.connectedScenes.first (which is unordered) with a search
through UIApplication.shared.connectedScenes to find the active UIWindowScene
(e.g., filter scenes where scene.activationState == .foregroundActive and scene
is UIWindowScene), then from that scene get the key window via
scene.windows.first(where: { $0.isKeyWindow }) and traverse its
rootViewController to find the topViewController; update the block that
currently declares scene/window/topViewController (the code that uses
connectedScenes.first and topViewController) to iterate scenes, pick the
foreground active UIWindowScene, and fall back safely if none found.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 68d6273d-dd91-49bb-b34b-31ef3ee11671

📥 Commits

Reviewing files that changed from the base of the PR and between 3f5a6c8 and 78d1519.

📒 Files selected for processing (1)

• ios/GoogleAuth.swift

[OrkhanAlikhanov]

One of the other libraries usedRCTPresentedViewController.

https://github.com/react-native-google-signin/google-signin/blob/aa1074e32666225a84d3597fcac38243dbdd186d/ios/RNGoogleSignin.mm#L240-L246

No swift equivalent but its code is similar o what's in this PR:

https://github.com/facebook/react-native/blob/5620b1ba11fcbe370611241afc7c3479f15c1abc/packages/react-native/React/Base/RCTUtils.mm#L664-L678