MacOS: Unable to find a specification for `React-Core` depended upon by `RNFileViewer`

[code-by]

My environment is the following:

System:
  OS: macOS 10.15.6
  Shell: 5.7.1 - /bin/zsh
Binaries:
  Node: 10.22.1 - /usr/local/opt/node@10/bin/node
  Yarn: 1.22.5 - /usr/local/bin/yarn
  npm: 6.14.6 - /usr/local/opt/node@10/bin/npm
  Watchman: 4.9.0 - /usr/local/bin/watchman
IDEs:
  Xcode: 11.7/11E801a - /usr/bin/xcodebuild
npmPackages:
  react: 16.8.3 => 16.8.3
  react-native: 0.59.9 => 0.59.9

react-native-file-viewer: "2.1.4"

when in /ios dir try pod install:

[!] Unable to find a specification for `React-Core` depended upon by `RNFileViewer`

You have either:
 * out-of-date source repos which you can update with `pod repo update` or with `pod install --repo-update`.
 * mistyped the name or version.
 * not added the source repo that hosts the Podspec to your Podfile.

Have do all manual steps for iOS setup

[code-by]

This helped to solve problem:
change line 16 in
RNFileViewer.podspec to s.dependency "React/Core"

[vinzscam]

Fixed by #86