Cannot add as an iOS dependency in pubspec.yaml

[Larpoux]

When I add 'flutter_lua: ^0.3.1' in my dev_dependencies I get the following error message when building for the ios Simulator 👎 [!] Unable to determine Swift version for the following pods:

- `flutter_lua` does not specify a Swift version and none of the targets (`Runner`) integrating it have the `SWIFT_VERSION` attribute set. Please contact the author or set the `SWIFT_VERSION` attribute in at least one of the targets that integrate this pod.

/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/installer/xcode/target_validator.rb:115:in `verify_swift_pods_swift_version'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/installer/xcode/target_validator.rb:37:in `validate!'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/installer.rb:459:in `validate_targets'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/installer.rb:138:in `install!'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/command/install.rb:48:in `run'
/Library/Ruby/Gems/2.3.0/gems/claide-1.0.2/lib/claide/command.rb:334:in `run'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/lib/cocoapods/command.rb:52:in `run'
/usr/local/Cellar/cocoapods/1.6.1/libexec/gems/cocoapods-1.6.1/bin/pod:55:in `<top (required)>'
/usr/local/Cellar/cocoapods/1.6.1/libexec/bin/pod:22:in `load'
/usr/local/Cellar/cocoapods/1.6.1/libexec/bin/pod:22:in `<main>'

Error running pod install Error launching application on iPhone 6s.

[artob]

Problem reproduced with Flutter 1.5.4 and flutter_lua 0.3.1.

[artob]

Relevant: https://stackoverflow.com/q/50458556