Add a way to build swift code as part of the executorch runtime framework

Author: shoumikhin

extension/apple/CMakeLists.txt

@@ -11,26 +11,29 @@
 
 cmake_minimum_required(VERSION 3.19)
 
+enable_language(Swift)
+
 # Source root directory for executorch.
 if(NOT EXECUTORCH_ROOT)
   set(EXECUTORCH_ROOT ${CMAKE_CURRENT_SOURCE_DIR}/../..)
 endif()
 
 add_library(extension_apple)
 
-file(GLOB EXPORTED_SOURCES
+file(GLOB OBJC_SOURCES
   ExecuTorch/Exported/*.m
   ExecuTorch/Exported/*.mm
-)
-
-file(GLOB INTERNAL_SOURCES
   ExecuTorch/Internal/*.m
   ExecuTorch/Internal/*.mm
 )
 
+file(GLOB SWIFT_SOURCES
+  ExecuTorch/Exported/*.swift
+)
+
 target_sources(extension_apple PRIVATE
-  ${EXPORTED_SOURCES}
-  ${INTERNAL_SOURCES}
+  ${OBJC_SOURCES}
+  ${SWIFT_SOURCES}
 )
 
 target_include_directories(extension_apple
@@ -43,9 +46,41 @@ target_link_libraries(extension_apple
   PRIVATE executorch ${FOUNDATION_FRAMEWORK}
 )
 
-target_compile_options(extension_apple PUBLIC ${_common_compile_options})
-target_compile_options(extension_apple PRIVATE
+set_source_files_properties(${OBJC_SOURCES} PROPERTIES COMPILE_FLAGS
   "-fobjc-arc"
   "-fno-exceptions"
   "-fno-rtti"
 )
+
+set(MODULE_MAP_DIR ${CMAKE_CURRENT_BINARY_DIR}/module)
+set(MODULE_MAP_FILE ${MODULE_MAP_DIR}/module.modulemap)
+
+configure_file(
+  "${CMAKE_CURRENT_SOURCE_DIR}/ExecuTorch/Exported/ExecuTorch.h"
+  "${MODULE_MAP_DIR}/ExecuTorch.h"
+  COPYONLY
+)
+
+file(MAKE_DIRECTORY ${MODULE_MAP_DIR})
+file(WRITE ${MODULE_MAP_FILE}
+"module ExecuTorch {
+  umbrella header \"ExecuTorch.h\"
+  export *
+}
+")
+
+set(SWIFT_CLANG_INTEROP_FLAGS "-Xcc -fmodule-map-file=${MODULE_MAP_FILE} -I ${MODULE_MAP_DIR}")
+
+set_target_properties(extension_apple PROPERTIES
+  Swift_MODULE_NAME "ExecuTorch"
+  Swift_FLAGS "${SWIFT_CLANG_INTEROP_FLAGS}"
+  XCODE_ATTRIBUTE_SWIFT_MODULE_NAME "ExecuTorch"
+  XCODE_ATTRIBUTE_BUILD_LIBRARY_FOR_DISTRIBUTION YES
+  XCODE_ATTRIBUTE_SWIFT_ENABLE_TESTABILITY YES
+  XCODE_ATTRIBUTE_OTHER_SWIFT_FLAGS "${SWIFT_CLANG_INTEROP_FLAGS}"
+)
+
+add_custom_command(
+  TARGET extension_apple POST_BUILD
+  COMMAND ${CMAKE_COMMAND} -E rm -rf ${MODULE_MAP_DIR}
+)