For [email protected]
the following did the trick for me:
1) Check your paths, open your .xcodeproj (not .xcworkspace) file and:
go to File > Project Settings > Advanced
custom > Relative to workspace
'build/Build/Products'
'build/Build/Intermediates'
2) Run rm -rf ios/build
in your project's root directory
3) Close your react packager
4) Run react-native run-ios
again