[AggregateXCConfig] Break down #generate

lib/cocoapods/generator/xcconfig/aggregate_xcconfig.rb

@@ -54,10 +54,42 @@ module Pod
             'PODS_ROOT' => target.relative_pods_root,
             'GCC_PREPROCESSOR_DEFINITIONS' => '$(inherited) COCOAPODS=1',
           }
+          @xcconfig = Xcodeproj::Config.new(config)
+
+          @xcconfig.merge!(merged_user_target_xcconfigs)
+
+          generate_settings_to_import_pod_targets
+
+          XCConfigHelper.add_target_specific_settings(target, @xcconfig)
+
+          generate_vendored_build_settings
+          generate_other_ld_flags
+
+          # TODO: Need to decide how we are going to ensure settings like these
+          # are always excluded from the user's project.
+          #
+          # See https://github.com/CocoaPods/CocoaPods/issues/1216
+          @xcconfig.attributes.delete('USE_HEADERMAP')
+
+          generate_ld_runpath_search_paths if target.requires_frameworks?
+
+          @xcconfig
+        end
 
+        #---------------------------------------------------------------------#
+
+        private
+
+        # Add build settings, which ensure that the pod targets can be imported
+        # from the integrating target by all sort of imports, which are:
+        #  - `#import <…>`
+        #  - `#import "…"`
+        #  - `@import …` / `@import …;`
+        #
+        def generate_settings_to_import_pod_targets
           if target.requires_frameworks?
             # Framework headers are automatically discoverable by `#import <…>`.
-            header_search_paths = pod_targets.map do |target|
+            header_search_paths = target.pod_targets.map do |target|
               if target.scoped?
                 "$PODS_FRAMEWORK_BUILD_PATH/#{target.product_name}/Headers"
               else
@@ -72,7 +104,7 @@ module Pod
             if target.pod_targets.any? { |t| t.should_build? && t.scoped? }
               build_settings['FRAMEWORK_SEARCH_PATHS'] = '$(inherited) "$PODS_FRAMEWORK_BUILD_PATH"'
             end
-            config.merge!(build_settings)
+            @xcconfig.merge!(build_settings)
           else
             # Make headers discoverable from $PODS_ROOT/Headers directory
             header_search_paths = target.sandbox.public_headers.search_paths(target.platform)
@@ -82,46 +114,50 @@ module Pod
               # by `#import <…>`
               'OTHER_CFLAGS' => '$(inherited) ' + XCConfigHelper.quote(header_search_paths, '-isystem'),
             }
-            config.merge!(build_settings)
+            @xcconfig.merge!(build_settings)
           end
+        end
 
-          @xcconfig = Xcodeproj::Config.new(config)
-
-          XCConfigHelper.add_target_specific_settings(target, @xcconfig)
-
-          pod_targets.each do |pod_target|
+        # Add custom build settings and required build settings to link to
+        # vendored libraries and frameworks.
+        #
+        # @note
+        #   In case of generated pod targets, which require frameworks, the
+        #   vendored frameworks and libraries are already linked statically
+        #   into the framework binary and must not be linked again to the
+        #   user target.
+        #
+        def generate_vendored_build_settings
+          target.pod_targets.each do |pod_target|
             unless pod_target.should_build? && pod_target.requires_frameworks?
-              # In case of generated pod targets, which require frameworks, the
-              # vendored frameworks and libraries are already linked statically
-              # into the framework binary and must not be linked again to the
-              # user target.
               XCConfigHelper.add_settings_for_file_accessors_of_target(pod_target, @xcconfig)
             end
+          end
+        end
 
-            # Add pod target to list of frameworks / libraries that are
-            # linked with the user’s project.
-            if pod_target.should_build?
-              if pod_target.requires_frameworks?
-                @xcconfig.merge!('OTHER_LDFLAGS' => %(-framework "#{pod_target.product_basename}"))
-              else
-                @xcconfig.merge!('OTHER_LDFLAGS' => %(-l "#{pod_target.product_basename}"))
-              end
+        # Add pod target to list of frameworks / libraries that are linked
+        # with the user’s project.
+        #
+        def generate_other_ld_flags
+          other_ld_flags = target.pod_targets.select(&:should_build?).map do |pod_target|
+            if pod_target.requires_frameworks?
+              %(-framework "#{pod_target.product_basename}")
+            else
+              %(-l "#{pod_target.product_basename}")
             end
           end
 
-          @xcconfig.merge!(merged_user_target_xcconfigs)
-
-          # TODO: Need to decide how we are going to ensure settings like these
-          # are always excluded from the user's project.
-          #
-          # See https://github.com/CocoaPods/CocoaPods/issues/1216
-          @xcconfig.attributes.delete('USE_HEADERMAP')
-
-          generate_ld_runpath_search_paths if target.requires_frameworks?
-
-          @xcconfig
+          @xcconfig.merge!('OTHER_LDFLAGS' => other_ld_flags.join(' '))
         end
 
+        # Ensure to add the default linker run path search paths as they could
+        # be not present due to being historically absent in the project or
+        # target template or just being removed by being superficial when
+        # linking third-party dependencies exclusively statically. This is not
+        # something a project needs specifically for the integration with
+        # CocoaPods, but makes sure that it is self-contained for the given
+        # constraints.
+        #
         def generate_ld_runpath_search_paths
           ld_runpath_search_paths = ['$(inherited)']
           if target.platform.symbolic_name == :osx