This was my issue while trying to integrate Firebase to my Xcode project using cocoapods
library not found for -lGoogleToolboxForMac
linker command failed with exit code 1 (use -v to see invocation)
After hours of searching and trying out various fixes listed in the stackoverflow, my issue was finally fixed doing following steps
Do this for all targets.
ios/Pods
)pod update
Voila! All linker errors will be gone.