Use relative paths when installing module pods (#37738)

packages/flutter_tools/templates/module/ios/library/Flutter.tmpl/podhelper.rb.tmpl

@@ -32,7 +32,13 @@ def install_flutter_engine_pod
     FileUtils.cp(File.join(debug_framework_dir, 'Flutter.podspec'), engine_dir)
   end
 
-  pod 'Flutter', :path => engine_dir, :inhibit_warnings => true
+  # Keep pod path relative so it can be checked into Podfile.lock.
+  # Process will be run from project directory.
+  engine_pathname = Pathname.new engine_dir
+  project_directory_pathname = Pathname.new Dir.pwd
+  relative = engine_pathname.relative_path_from project_directory_pathname
+
+  pod 'Flutter', :path => relative.to_s, :inhibit_warnings => true
 end
 
 # Install Flutter plugin pods.
@@ -46,9 +52,15 @@ end
 #                                          MyApp/my_flutter/.ios/Flutter/../..
 def install_flutter_plugin_pods(flutter_application_path)
   flutter_application_path ||= File.join('..', '..')
-  pod 'FlutterPluginRegistrant', :path => File.join(__dir__, 'FlutterPluginRegistrant'), :inhibit_warnings => true
 
-  symlinks_dir = File.join(__dir__, '.symlinks')
+  # Keep pod path relative so it can be checked into Podfile.lock.
+  # Process will be run from project directory.
+  current_directory_pathname = Pathname.new __dir__
+  project_directory_pathname = Pathname.new Dir.pwd
+  relative = current_directory_pathname.relative_path_from project_directory_pathname
+  pod 'FlutterPluginRegistrant', :path => File.join(relative, 'FlutterPluginRegistrant'), :inhibit_warnings => true
+
+  symlinks_dir = File.join(relative, '.symlinks')
   FileUtils.mkdir_p(symlinks_dir)
   plugin_pods = parse_KV_file(File.join(flutter_application_path, '.flutter-plugins'))
   plugin_pods.map do |r|
@@ -79,13 +91,12 @@ def install_flutter_application_pod(flutter_application_path)
     `echo "static const int Moo = 88;" | xcrun clang -x c -dynamiclib -o "#{app_framework_dylib}" -`
   end
 
-  pod '{{projectName}}', :path => __dir__, :inhibit_warnings => true
-
-  # Use relative paths for script phase paths since these strings will likely be checked into source controls.
+  # Keep pod and script phase paths relative so they can be checked into source control.
   # Process will be run from project directory.
-  current_directory_pathname = Pathname.new __dir__.to_s
+  current_directory_pathname = Pathname.new __dir__
   project_directory_pathname = Pathname.new Dir.pwd
   relative = current_directory_pathname.relative_path_from project_directory_pathname
+  pod '{{projectName}}', :path => relative.to_s, :inhibit_warnings => true
 
   flutter_export_environment_path = File.join('${SRCROOT}', relative, 'flutter_export_environment.sh');
   script_phase :name => 'Run Flutter Build Script',