[VOGO Technology]

Real-world case: Firebase, Google Sign-In, MLKit (mobile_scanner) & CocoaPods

This post documents a real production-level dependency conflict on iOS in a large Flutter project. The goal is to explain why these issues happen, how to diagnose them correctly, and how to apply a single, stable fix — not temporary hacks.

Technical Context

Stack involved:

• Flutter (large-scale app, many plugins)
• Firebase (firebase_core, firebase_messaging, firebase_auth)
• Google Sign-In
• MLKit via mobile_scanner
• CocoaPods (iOS)

Main symptom:

CocoaPods could not find compatible versions for pod “GoogleUtilities/*”

Seen as:

• GoogleUtilities/UserDefaults
• GoogleUtilities/Environment
• mixed constraints: ~> 7.x, < 8.0, ~> 8.0

Why this happens (the real reason)

This is not a Flutter issue.
This is not a CocoaPods bug.

It is a structural incompatibility inside the Google iOS ecosystem.

1. Firebase

• Firebase 10.x → GoogleUtilities 7.x
• Firebase 11.x → GoogleUtilities 8.x

2. Google Sign-In

• GoogleSignIn 8.x → GoogleUtilities 8.x (via AppCheck)

3. MLKit (mobile_scanner)

• mobile_scanner ≤ 5.x
  → MLKitCommon 11.x
  → GoogleUtilities < 8.0

💥 Result:

• Firebase 10.x requires 7.x
• GoogleSignIn 8.x requires 8.x
• MLKit blocks < 8.0

➡️ There is no version combination that can satisfy all three.
CocoaPods correctly refuses to resolve this graph.

The common mistake (and why it fails)

Forcing Firebase in Podfile:

$FirebaseSDKVersion = ‘10.25.0’

This may:

• temporarily “fix” Firebase
• but immediately breaks Google Sign-In
• and still conflicts with MLKit

This is an anti-pattern in modern Flutter projects.

The correct solution (one stable fix)

Core rule

👉 All Google dependencies must be aligned on the same major generation (8.x)

That means:

• Firebase 11.x
• GoogleSignIn 8.x
• MLKit compatible with GoogleUtilities 8.x

Final working fix (tested and stable)

1️⃣ pubspec.yaml

dependencies:

firebase_core: ^3.15.2

firebase_messaging: ^15.2.10

firebase_auth: ^5.7.0

google_sign_in: ^6.3.0

mobile_scanner: ^7.1.4

⚠️ Important: mobile_scanner 7.x is mandatory.
Older versions explicitly block GoogleUtilities < 8.0.

2️⃣ ios/Podfile

Remove any Firebase pinning.

Correct:

platform :ios, ‘15.0’

ENV[‘COCOAPODS_DISABLE_STATS’] = ‘true’

❌ Incorrect:

$FirebaseSDKVersion = ‘10.25.0’

3️⃣ Clean rebuild (strict order)

cd <project-root>

 

flutter clean

rm -rf .dart_tool pubspec.lock

flutter pub get

 

ls ios/Flutter/Generated.xcconfig   # must exist

 

cd ios

rm -rf Pods Podfile.lock .symlinks Runner.xcworkspace

pod repo update

pod install –repo-update

4️⃣ Xcode

Open only:

ios/Runner.xcworkspace

Never open Runner.xcodeproj.

Why this fix works

• Eliminates all 7.x vs 8.x conflicts
• Avoids forcing CocoaPods
• Follows Google’s official dependency direction
• Future-proof against SDK upgrades
• Prevents subtle runtime crashes (AppCheck, Messaging, Sign-In)

Key lessons (for large Flutter projects)

1. Never mix Google dependency generations
2. Podfile pinning is a last resort, not a solution
3. In Flutter, dependency issues are solved in pubspec.yaml, not CocoaPods
4. mobile_scanner is a critical dependency on iOS
5. If you see GoogleUtilities/* errors → you have a version alignment problem

Conclusion

If your Flutter iOS project uses Firebase, Google Sign-In, and MLKit:

• version alignment is mandatory
• temporary workarounds will fail again
• the only stable solution is a coherent, modern Google stack

Save this post as an advanced troubleshooting reference — it can save days of debugging next time.

 

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