はじめに

Failed to install CocoaPods for the current user.

It will not be possible to install Cocoapods in the generated Xcode project which will result in link errors when building your application.

For more information see:
  https://guides.cocoapods.org/using/getting-started.html


'gem install cocoapods --user-install' failed with code (1):


WARNING:  You don't have /Users/baba_s/.gem/ruby/2.6.0/bin in your PATH,
      gem executables will not run.
ERROR:  Error installing cocoapods:
    The last version of securerandom (>= 0.3) to support your Ruby & RubyGems was 0.3.2. Try installing it with `gem install securerandom -v 0.3.2` and then running the current command again
    securerandom requires Ruby version >= 3.1.0. The current ruby version is 2.6.10.210.


UnityEngine.Debug:LogError (object)
Google.Logger:Log (string,Google.LogLevel) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/Logger.cs:136)
Google.IOSResolver:Log (string,bool,Google.LogLevel) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/IOSResolver/src/IOSResolver.cs:1243)
Google.IOSResolver:LogToDialog (string,bool,Google.LogLevel) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/IOSResolver/src/IOSResolver.cs:1254)
Google.IOSResolver/<>c__DisplayClass181_0:<InstallCocoapods>b__0 (int,Google.IOSResolver/CommandItem[],GooglePlayServices.CommandLine/Result,GooglePlayServices.CommandLineDialog) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/IOSResolver/src/IOSResolver.cs:1880)
Google.IOSResolver/<>c__DisplayClass205_1:<RunCommandsAsync>b__0 (GooglePlayServices.CommandLine/Result) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/IOSResolver/src/IOSResolver.cs:2565)
GooglePlayServices.CommandLineDialog/ProgressReporter:SignalComplete () (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/AndroidResolver/src/CommandLineDialog.cs:116)
GooglePlayServices.CommandLineDialog/ProgressReporter:CommandLineToolCompletion (GooglePlayServices.CommandLine/Result) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/AndroidResolver/src/CommandLineDialog.cs:107)
GooglePlayServices.CommandLine/<>c__DisplayClass4_1:<RunAsync>b__1 () (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/AndroidResolver/src/CommandLine.cs:137)
Google.RunOnMainThread:ExecuteNext () (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:486)
Google.RunOnMainThread/<>c:<ExecuteAllUnnested>b__28_0 () (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:536)
Google.RunOnMainThread:RunAction (System.Action) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:343)
Google.RunOnMainThread:ExecuteAllUnnested (bool) (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:530)
Google.RunOnMainThread:ExecuteAll () (at /Users/amaurice/Documents/GitHub/unity-jar-resolver/source/VersionHandlerImpl/src/RunOnMainThread.cs:512)
UnityEditor.EditorApplication:Internal_CallUpdateFunctions () (at /Users/bokken/build/output/unity/unity/Editor/Mono/EditorApplication.cs:380)

新しい Mac で、Firebase を使用している Unity プロジェクトを
iOS プラットフォームで起動したところ、上記のエラーが発生する現象に遭遇した。

上記 2 つのサイト様の方法でエラーを解決できたので
備忘録として行った手順を書き残しておきます。

手順

Homebrew を公式サイトの手順でインストール

インストール完了時に Next steps: に表示されたコマンドを実行

echo >> /Users/baba_s/.zprofile
echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> /Users/baba_s/.zprofile
eval "$(/opt/homebrew/bin/brew shellenv)"

以下のコマンドで Homebrew がインストールできたか確認

brew -v

以下のコマンドで rbenv をインストール

brew install rbenv

~/.zshrc を作成して以下の内容を記述して保存

export PATH="$HOME/.rbenv/bin:$PATH"
eval "$(rbenv init -)"

インストール可能な安定版の Ruby のバージョンを表示

rbenv install -l

バージョンを指定して Ruby をインストール

rbenv install 3.2.8

Ruby をインストールできたか確認

rbenv versions

使用する Ruby のバージョンを指定

rbenv global 3.2.8

Ruby のバージョンを指定できたか確認

rbenv versions

シェルを再起動

exec $SHELL -l

使用している Ruby のバージョンを確認

ruby -v

cocoapods をインストール

sudo gem install -n /usr/local/bin cocoapods
pod setup

Unity プロジェクトを開いてエラーが発生しなくなったことを確認