Firebase Undefined symbols for architecture x86_64

Question

I am using firebase as part of a project I am working on in iOS, and I just stumbled upon the following linking error when I try to compile my code against an iPhone 6 or 7

Answer 1

Had the same problem, and for me the issue was that I had imported the FirebaseMessaging framework manually, by downloading the entire Firebase SDK and then manually importing the Messaging framework into the project (I didn't use Cocoapods or Carthage). I didn't import the other framework in the same folder, "Protobuf.framework". Once adding Protobuf and making sure the target memberships included my project target, it worked.