Keep Flutter MMKV Core linked with SwiftPM #1676

flutter/mmkv_ios/darwin/mmkv_ios/Sources/mmkv_ios/MMKVPlugin.mm

@@ -25,6 +25,8 @@
 @implementation MMKVPlugin
 
 + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar> *)registrar {
+    mmkvEnsureCoreLinked();
+
     FlutterMethodChannel *channel = [FlutterMethodChannel
         methodChannelWithName:@"mmkv"
               binaryMessenger:[registrar messenger]];

flutter/mmkv_ios/darwin/mmkv_ios/Sources/mmkv_ios/flutter-bridge.h

@@ -19,6 +19,12 @@ using ErrorCallback_t = uint32_t (*)(const char *mmapID, uint32_t errorType);
 using ContenctChangeCallback_t = void (*)(const char *mmapID);
 using LogCallback_t = void (*)(uint32_t level, const char *file, int32_t line, const char *funcname, const char *message);
 
+// SwiftPM packages native targets as static archives. Dart resolves the FFI
+// entry points with dlsym(), so those lookups don't create linker references
+// that would extract this translation unit from the archive. MMKVPlugin calls
+// this anchor to keep the bridge, and therefore MMKVCore, in the final binary.
+extern "C" void mmkvEnsureCoreLinked(void);
+
 @interface MyMMKVHandler : NSObject<MMKVHandler>
 
 @property (atomic, assign) ErrorCallback_t errorCallback;

flutter/mmkv_ios/darwin/mmkv_ios/Sources/mmkv_ios/flutter-bridge.mm

@@ -27,6 +27,12 @@
 
 using namespace std;
 
+extern "C" __attribute__((noinline, visibility("hidden"))) void mmkvEnsureCoreLinked(void) {
+    // The compiler must preserve this call even under whole-module optimization.
+    // Its relocation is what extracts this object from the SwiftPM archive.
+    __asm__ __volatile__("" ::: "memory");
+}
+
 MMKV_EXPORT void *mmkvInitialize(const char *rootDir, const char *groupDir, int32_t logLevel, LogCallback_t logCallback) {
     auto handler = [MyMMKVHandler getHandler];
     handler.logCallback = logCallback;