refactor swift shim

Sources/SDLSwift/CMakeLists.txt

@@ -0,0 +1,9 @@
+find_library(SDL3 SDL3 REQUIRED)
+
+add_library(SDLSwift INTERFACE)
+set_property(TARGET SDLSwift PROPERTY Swift_MODULE_NAME "SDL3")
+
+target_compile_options(SDLSwift INTERFACE "$<$<COMPILE_LANGUAGE:Swift>:-cxx-interoperability-mode=default>")
+target_include_directories(SDLSwift INTERFACE "${CMAKE_CURRENT_SOURCE_DIR}")
+
+target_link_libraries(SDLSwift INTERFACE ${SDL3})

Sources/SDLSwift/module.modulemap

@@ -0,0 +1,3 @@
+module SDL3 {
+  header "shim.h"
+}

Sources/SDLSwift/shim.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#include <SDL3/SDL.h>