ci(ios): cache native compilation with ccache

.github/workflows/ios.yml

@@ -39,6 +39,25 @@ jobs:
         run: bun install
         working-directory: example
 
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@14594264cd68ce8a2345dd349bc3d138a4ef85c8 # v1.327.0
+        with:
+          ruby-version: '4.0'
+          bundler-cache: true
+          working-directory: example
+
+      # Mirrors RN's scripts/xcode/ccache.conf, which only applies to its CC
+      # wrapper, not to the compiler launcher used here.
+      - name: Install and configure ccache
+        run: |
+          brew install ccache
+          ccache --set-config max_size=2G
+          ccache --set-config base_dir="$GITHUB_WORKSPACE"
+          ccache --set-config sloppiness=clang_index_store,file_stat_matches,include_file_ctime,include_file_mtime,ivfsoverlay,pch_defines,modules,system_headers,time_macros
+          ccache --set-config depend_mode=true
+          ccache --set-config file_clone=true
+          ccache --set-config inode_cache=true
+
       - name: Cache Pods
         id: cache-pods
         uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
@@ -48,9 +67,20 @@ jobs:
           path: example/ios/Pods
           key: ${{ hashFiles('example/ios/Podfile.lock') }}
 
+      # Sets ccache as Xcode's C_COMPILER_LAUNCHER, see example/ios/Podfile.
       - name: Install example Pods
         run: bun pods
         working-directory: example
+        env:
+          USE_CCACHE_LAUNCHER: 1
+
+      - name: Restore ccache
+        uses: actions/cache/restore@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: ~/Library/Caches/ccache
+          key: ccache-ios-Release-${{ github.sha }}-${{ github.run_attempt }}
+          restore-keys: |
+            ccache-ios-Release-
 
       # Simulator.app attaches the Mac keyboard by default, which hides the
       # software keyboard and leaves no Return key for the keyboard tests.
@@ -59,7 +89,20 @@ jobs:
 
       - name: Build iOS App
         run: |
-          bun example:ios:release
+          ccache --zero-stats
+          bun example:ios:release --extra-params "COMPILER_INDEX_STORE_ENABLE=NO"
+          ccache --show-stats -v
+
+      # Only main saves, PRs restore from it. Saved right after the build so a
+      # failing e2e run still warms the cache.
+      # TODO: drop the pull_request condition before merging, it's only here to
+      # measure warm builds on this PR.
+      - name: Save ccache
+        if: ${{ !cancelled() && (github.ref == 'refs/heads/main' || github.event_name == 'pull_request') }}
+        uses: actions/cache/save@5a3ec84eff668545956fd18022155c47e93e2684 # v4.2.3
+        with:
+          path: ~/Library/Caches/ccache
+          key: ccache-ios-Release-${{ github.sha }}-${{ github.run_attempt }}
 
       - name: Install e2e dependencies
         run: bun install

example/ios/Podfile

@@ -31,6 +31,26 @@ target 'PagerViewExample' do
       # :ccache_enabled => true
     )
 
+    # Xcode's compiler launcher keeps explicit modules enabled, unlike RN's
+    # ccache CC wrapper (USE_CCACHE), so don't combine the two.
+    if ENV['USE_CCACHE_LAUNCHER'] == '1'
+      ccache_path = `command -v ccache`.strip
+      if ccache_path.empty?
+        Pod::UI.warn('[Ccache] USE_CCACHE_LAUNCHER=1 but ccache was not found on PATH')
+      else
+        Pod::UI.puts("[Ccache] Using #{ccache_path} as C_COMPILER_LAUNCHER")
+        projects = [installer.pods_project]
+        projects += installer.aggregate_targets.map(&:user_project).compact
+        projects.uniq { |project| project.path }.each do |project|
+          project.build_configurations.each do |config|
+            config.build_settings['C_COMPILER_LAUNCHER'] = ccache_path
+            config.build_settings['CLANG_ENABLE_EXPLICIT_MODULES_WITH_COMPILER_LAUNCHER'] = 'YES'
+          end
+          project.save
+        end
+      end
+    end
+
     # Xcode rejects deployment targets below 15.0, and RN's own post_install
     # skips resource-bundle targets, so RNSVG's bundles keep the podspec's 12.4.
     installer.pods_project.targets.each do |target|