XcodeGen project spec sample

project.yml

name: {Project Name}

options:
  bundleIdPrefix: {Bundle ID Prefix}
  deploymentTarget:
    iOS: 13.0
  xcodeVersion: "11.3.1" # 変わらない？
  # findCarthageFrameworks: true # 余計なフレームワークまで追加されてしまうためコメントアウト
  carthageExecutablePath: mint run Carthage/Carthage carthage

targets:
  {Project Name}:
    type: application
    platform: iOS
    sources:
      - {Project Name}
      - path: "{Project Name}/Generated/MockResults.swift"
        optional: true
        type: file
      - path: "{Project Name}/Generated/R.generated.swift"
        optional: true
        type: file
    settings:
      base:
        INFOPLIST_FILE: {Project Name}/Info.plist
        # PRODUCT_BUNDLE_IDENTIFIER: {Bundle ID Prefix}.{Project Name} # `bundleIdPrefix` を指定しない場合はコメントイン
        CODE_SIGN_ENTITLEMENTS: Foo/Foo.entitlements
    dependencies:
      - carthage: Alamofire
      - carthage: Moya
      - carthage: ReactiveMoya
      - carthage: ReactiveSwift
      - carthage: RxCocoa
      - carthage: RxMoya
      - carthage: RxRelay
      - carthage: RxSwift
    preBuildScripts:
      - script: |
                "$PODS_ROOT/R.swift/rswift" generate "$SRCROOT/$TARGET_NAME/Generated/R.generated.swift"
        name: Generate Resources with R.swift
        inputFiles:
          - $TEMP_DIR/rswift-lastrun
        outputFiles:
          - $SRCROOT/$TARGET_NAME/Generated/R.generated.swift
      - script: |
                if which mint >/dev/null; then
                  rm -f $SRCROOT/$TARGET_NAME/Generated/MockResults.swift
                  mint run mockolo mockolo --sourcedirs $SRCROOT/$TARGET_NAME --destination $SRCROOT/$TARGET_NAME/Generated/MockResults.swift
                else
                  echo "warning: Mint not installed, download from https://github.com/yonaskolb/Mint"
                fi
        name: Generate Mocks with Mockolo
        outputFiles:
          - $SRCROOT/$TARGET_NAME/Generated/MockResults.swift
    postCompileScripts:
      - script: |
                if which mint >/dev/null; then
                  mint run swiftlint swiftlint autocorrect --format
                  mint run swiftlint swiftlint
                else
                  echo "warning: Mint not installed, download from https://github.com/yonaskolb/Mint"
                fi
        name: Run SwiftLint
      - script: |
                if ! which mint >/dev/null; then
                  echo "warning: Mint not installed, download from https://github.com/yonaskolb/Mint"
                  exit 0
                fi

                git_path=/usr/local/bin/git
                files=$($git_path diff --diff-filter=d --name-only -- "*.swift" "*.h" "*.m")
                if (test -z $files) || (test ${#files[@]} -eq 0); then
                  echo "no files changed."
                  exit 0
                fi

                options=""
                for file in $files
                do
                  options="$options $SRCROOT/$file"
                done

                mint run SpellChecker SpellChecker --yml $SRCROOT/spell-checker.yml -- $options
        name: Run SpellChecker

  {Project Name}Tests:
    type: bundle.unit-test
    platform: iOS
    sources:
      - {Project Name}Tests
    settings:
      base:
        INFOPLIST_FILE: {Project Name}Tests/Info.plist
        # PRODUCT_BUNDLE_IDENTIFIER: {Bundle ID Prefix}.{Project Name}Tests
    dependencies:
      - target: {Project Name}

  {Project Name}UITests:
    type: bundle.ui-testing
    platform: iOS
    sources:
      - {Project Name}UITests
    settings:
      base:
        INFOPLIST_FILE: {Project Name}UITests/Info.plist
        # PRODUCT_BUNDLE_IDENTIFIER: {Bundle ID Prefix}.{Project Name}UITests
    dependencies:
      - target: {Project Name}

schemes:
  {Project Name}:
    build:
      targets:
        {Project Name}: all
        # {Project Name}Tests: [test] # デフォルト？
        # {Project Name}UITests: [test] # デフォルト？
    run:
      config: Debug
    test:
      config: Debug
      gatherCoverageData: true
      coverageTargets:
        - {Project Name}
      targets:
        - name: {Project Name}Tests
          parallelizable: true
          randomExecutionOrder: true
        - name: {Project Name}UITests
          parallelizable: true
          randomExecutionOrder: true
    profile:
      config: Release
    analyze:
      config: Debug
    archive:
      config: Release

参考になりました．ちなみに xcodeVersion は

xcodeVersion: "11.3.1"

のように文字列で指定する必要がありますよ．

@KKK669 Qiitaに加えてこちらのご指摘もありがとうございますー！
修正しました。