firebase-ios-sdk: Undefined symbol: _OBJC_CLASS_$_FIRApp

Step 0: Are you in the right place?

• For issues or feature requests related to the code in this repository file a Github issue.
  • If this is a feature request please use the Feature Request template.
• For general technical questions, post a question on StackOverflow with the firebase tag.
• For general (non-iOS) Firebase discussion, use the firebase-talk google group.
• For backend issues, console issues, and other non-SDK help that does not fall under one of the above categories, reach out to Firebase Support.
• Once you’ve read this section and determined that your issue is appropriate for this repository, please delete this section.

[REQUIRED] Step 1: Describe your environment

• Xcode version: 12.5.1
• Firebase SDK version: _____
• Installation method: Carthage (select one)
• Firebase Component: Core, Auth (Auth, Core, Database, Firestore, Messaging, Storage, etc)

[REQUIRED] Step 2: Describe the problem

I’m using Carthage for install Firebase follow step by step from this: https://github.com/firebase/firebase-ios-sdk/blob/master/Carthage.md I can import Firebase/FirebaseAuth … and run without any problem, but when I’m using FirebaseApp.configure()… it built failed: ld: warning: Could not find or use auto-linked framework ‘Firebase’ Undefined symbols for architecture x86_64: “OBJC_CLASS$_FIRApp”, referenced from: objc-class-ref in AppDelegate.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Steps to reproduce:

What happened? How can we make the problem occur? This could be a description, log/console output, etc.

If you have a downloadable sample project that reproduces the bug you’re reporting, you will likely receive a faster response on your issue.

Relevant Code:

// TODO(you): code here to reproduce the problem