Flutter iOS build fail on running pod install

Issue

I'm trying to make a flutter plugin, so I created a plugin by steps provided on https://flutter.dev/docs/development/packages-and-plugins/developing-packages. I'm getting an error when I try to run an ios example. Below is the log I'm getting while running the ios example app.

Can anyone help me with this?

Running pod install...
CocoaPods' output:
    Analyzing dependencies

    Inspecting targets to integrate
      Using `ARCHS` setting to build architectures of target `Pods-Runner`: (``)

    Fetching external sources
    -> Fetching podspec for `Flutter` from `.symlinks/flutter/ios`
    -> Fetching podspec for `flutter_plugin` from `.symlinks/plugins/flutter_plugin/ios`

    Resolving dependencies of `Podfile`

    Comparing resolved specification to the sandbox manifest
      A Flutter
      A flutter_plugin

    Downloading dependencies

    -> Installing Flutter (1.0.0)

    -> Installing flutter_plugin (0.0.1)
      - Running pre-install hooks
    [!] Unable to determine Swift version for the following pods:

    - `flutter_plugin` does not specify a Swift version and none of the targets (`Runner`) integrating it has 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.

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

Error output from CocoaPods:
        [33mWARNING: CocoaPods requires your terminal to be using UTF-8 encoding.
        Consider adding the following to ~/.profile:
Error running pod install

Solution

Got the issue. when we create a plugin by command on the terminal it creates a plugin with default Java for Android and Objective-C for iOS. It can be changed to Kotlin for Android and Swift for iOS by using a command, but it will add support to only android/ and ios/ in the root folder. This does not change the example code in example/ directory. The provided examples are still in Java for Android and Objective-C for iOS. So then I created a plugin from Android Studio, I created a Swift support for iOS by checking an option 'Include Swift support for ios code', it created an example with swift instead of Objective-C. Then the issue is solved.

Answered By - Amol Gangadhare