【Unity】Google Mobile Ads 更新後にiOSビルドに失敗する

Google Mobile Ads を v6.1.2 にアプデしたら
CocoaPods関連でエラーがあったので備忘録的にまとめておきます。

不具合

iOSビルド時に以下のエラーが出力されビルドが失敗する

iOS framework addition failed due to a CocoaPods installation failure. This will will likely result in an non-functional Xcode project.

After the failure, "pod repo update" was executed and succeeded. "pod install" was then attempted again, and still failed. This may be due to a broken CocoaPods installation. See: https://guides.cocoapods.org/using/troubleshooting.html for potential solutions.

pod install output:

Analyzing dependencies
[!] `Google-Mobile-Ads-SDK` requires CocoaPods version `>= 1.9.0`, which is not satisfied by your current version, `1.8.4`.

pod repo update output:

Updating spec repo `cocoapods`

原因

MacにインストールされているCocoaPodsのバージョンが古い

[!] `Google-Mobile-Ads-SDK` requires CocoaPods version `>= 1.9.0`, which is not satisfied by your current version, `1.8.4`.

解決方法

以下コマンドで CocoaPods を指定バージョンに更新

sudo gem install -v1.9.0 cocoapods -n /usr/local/bin

しかし、以下のエラーが発生

Building native extensions. This could take a while...
ERROR:  Error installing cocoapods:
    ERROR: Failed to build gem native extension.

    current directory: /Library/Ruby/Gems/2.6.0/gems/ffi-1.15.4/ext/ffi_c
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/ruby -I /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0 -r ./siteconf20211229-38719-1beaswp.rb extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/$(RUBY_BASE_NAME)
    --with-ffi_c-dir
    --without-ffi_c-dir
    --with-ffi_c-include
    --without-ffi_c-include=${ffi_c-dir}/include
    --with-ffi_c-lib
    --without-ffi_c-lib=${ffi_c-dir}/lib
    --enable-system-libffi
    --disable-system-libffi
    --with-libffi-config
    --without-libffi-config
    --with-pkg-config
    --without-pkg-config
/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:467:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:546:in `block in try_link0'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/tmpdir.rb:93:in `mktmpdir'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:543:in `try_link0'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:570:in `try_link'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:672:in `try_ldflags'
    from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/mkmf.rb:1832:in `pkg_config'
    from extconf.rb:9:in `system_libffi_usable?'
    from extconf.rb:42:in `<main>'

To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.15.4/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Library/Ruby/Gems/2.6.0/gems/ffi-1.15.4 for inspection.
Results logged to /Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.15.4/gem_make.out

rubyバージョンが古いのが原因、
こちらを参考に最新版3.1.0(2021/12/29時点)をインストール
(rubyのバージョンが切り替わらない場合はこちらを参考)

先程のコマンドを再実行、無事、CocoaPods のアプデに成功

と思ったら、iOSビルドで別のエラー発生、、

iOS framework addition failed due to a CocoaPods installation failure. This will will likely result in an non-functional Xcode project.

After the failure, "pod repo update" was executed and succeeded. "pod install" was then attempted again, and still failed. This may be due to a broken CocoaPods installation. See: https://guides.cocoapods.org/using/troubleshooting.html for potential solutions.

pod install output:

Analyzing dependencies
[!] `GoogleAppMeasurement` requires CocoaPods version `>= 1.10.2`, which is not satisfied by your current version, `1.9.0`.

CocoaPods を 1.10.2 以上にする必要あり

[!] `GoogleAppMeasurement` requires CocoaPods version `>= 1.10.2`, which is not satisfied by your current version, `1.9.0`.

バージョンを書き換えて再実行

今度は無事にiOSビルドが通りました！ いやはや、とても疲れました・・^_^ ;

参考

MacでRubyをインストールする方法をわかりやすく解説【初心者必見】 | 侍エンジニアブログ
Rubyのバージョンが切り替わらない時の対処法！ #Ruby - Qiita