I could not add the framework manually.
Using Pods, it gave out this mistake. What I had to do in the end was refactor every import <GoogleMobileAds/GADActualRealHeader.h> to be "GADActualRealHeader".
Seems like it does not recognise it should have a GoogleMobileAds lib.
Problem keeps appearing and disappearing on different branches and new pod installs.
I mean I know it's Google working on iOS platform, but still it should not be THAT bad.