Getting this error while building a react-native iOS app on xcode.
Started getting this error after npm install and rpm linking react-native-fs library. But
Go to iOS folder in your project and install pod -
$ pod install
If you are getting any error in installation of pod type command-
$ xcode-select -p
Result should be - /Applications/Xcode.app/Contents/Developer
If the path is incorrect then open your iOS project in Xcode and go to: Xcode->preferences->command line tools-> select Xcode
And again install the pod your issue will be fixed.