‘GoogleUtilities/GULAppEnvironmentUtil.h’ file not found

Added Firebase pod. Worked fine on Xcode 9.4. But after updating Xcode to 10.1, the above issue is showing. Interestingly, the file was there under environment folder in the pods section.

Solution:

1. Clean your build.
2. In the pod file, make deployment target 9.0 or higher (I did, but this step may not be mandatory)
3. Exit Xcode.
4. Open terminal.
5. Run “sudo gem install cocoapods” (it will update your cocoapods version to latest)
6. Run “pod update”
7. Open your project & build.

Error should be gone.