Firebase Undefined symbols for architecture x86_64

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 simulator for testing.

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_GTMSessionUploadFetcher", referenced from:
      objc-class-ref in FirebaseStorage(FIRStorageUploadTask_d5061b1e2b5f1bb249816cc5fc42ff62.o)
  "_OBJC_CLASS_$_GTMLogger", referenced from:
      objc-class-ref in FirebaseMessaging(GIPReachability_ae5504e4a6a28a1d8997c6f38e8bff8b.o)
  "_kGTMSessionUploadFetcherStandardChunkSize", referenced from:
      -[FIRStorageUploadTask enqueue] in FirebaseStorage(FIRStorageUploadTask_d5061b1e2b5f1bb249816cc5fc42ff62.o)
  "_GTMFetcherStandardUserAgentString", referenced from:
      -[FIRAuthBackendRPCIssuerImplementation init] in FirebaseAuth(FIRAuthBackend_ea73237c278bd1b78e1c76db2a16775a.o)
  "_OBJC_CLASS_$_GTMSessionFetcher", referenced from:
      objc-class-ref in FirebaseStorage(FIRStorageDownloadTask_c390366e83519f6636ca985ecb70e5d0.o)
      objc-class-ref in FirebaseStorage(FIRStorage_691ea9ac7cb4d224d37df2ff8a911989.o)
  "_OBJC_CLASS_$_GTMSessionFetcherService", referenced from:
      objc-class-ref in FirebaseAuth(FIRAuthBackend_ea73237c278bd1b78e1c76db2a16775a.o)
      objc-class-ref in FirebaseStorage(FIRStorage_691ea9ac7cb4d224d37df2ff8a911989.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

I am using Xcode 8.2.1, swift 3.0, and I also have the following Pod file in my project

pod 'Braintree'
pod 'Firebase/Auth'
pod 'Firebase/Database'
pod 'Firebase/Core'
pod 'Firebase/Storage'
pod 'Firebase/Messaging'
pod 'Firebase/RemoteConfig'
pod 'GeoFire', :git=>'https://github.com/firebase/geofire-objc.git'
pod 'ObjectMapper', '~> 2.2'

I have done a pod update in case something was out of date, but no luck. The code compiles and runs fine when I use an iPhone 4 or 5 simulator.

Edit:

I have set Build Active architectures to No, in valid architectures I have listed arm64, armv7, armv7s and now Objectmapper is failing even though import ObjectMapper is declared in the file

 Use of undeclared type 'Mappable'

Any help would be greatly appreciated! Thank you in advance.

George.

Solution

It seems to be a glitch with derived data. I quitted out of Xcode, I removed all Derived Data in /Users/USER_NAME/Library/Developer/Xcode/PROJECT_NAME

Restarted Xcode, compiled and all works as expected, no need to change anything in Active Architecture Only or anything.