multi-process mode

README.md

@@ -113,7 +113,8 @@ import { MMKV } from 'react-native-mmkv'
 export const storage = new MMKV({
   id: `user-${userId}-storage`,
   path: `${USER_DIRECTORY}/storage`,
-  encryptionKey: 'hunter2'
+  encryptionKey: 'hunter2',
+  mode: 'single-mode'
 })
 ```
 
@@ -124,7 +125,7 @@ The following values can be configured:
 * `id`: The MMKV instance's ID. If you want to use multiple instances, use different IDs. For example, you can separate the global app's storage and a logged-in user's storage. (required if `path` or `encryptionKey` fields are specified, otherwise defaults to: `'mmkv.default'`)
 * `path`: The MMKV instance's root path. By default, MMKV stores file inside `$(Documents)/mmkv/`. You can customize MMKV's root directory on MMKV initialization (documentation: [iOS](https://github.com/Tencent/MMKV/wiki/iOS_advance#customize-location) / [Android](https://github.com/Tencent/MMKV/wiki/android_advance#customize-location))
 * `encryptionKey`: The MMKV instance's encryption/decryption key. By default, MMKV stores all key-values in plain text on file, relying on iOS's/Android's sandbox to make sure the file is encrypted. Should you worry about information leaking, you can choose to encrypt MMKV. (documentation: [iOS](https://github.com/Tencent/MMKV/wiki/iOS_advance#encryption) / [Android](https://github.com/Tencent/MMKV/wiki/android_advance#encryption))
-
+- `mode`: The MMKV mode. You can set its value to `multi-process` to support simultaneous read-write access between process at the cost of performance. This is useful when you want to share data between your react-native app and native extensions such as widgets. On iOS additionally you need to set the AppGroup bundle property to share the same storage between your app and its extensions. If you don't set the AppGroup, the mode will be ignored and the mmkv will use the default storage location. More information on AppGroups [here](https://github.com/mrousavy/react-native-mmkv/tree/master#app-groups). For backward compatibility, the mode is set to `single-process` on android and for iOS it'll use `multi-process` if `AppGroup` exists.
 ### Set
 
 ```js

android/src/main/cpp/MmkvHostObject.cpp

@@ -14,15 +14,14 @@
 #include <vector>
 
 MmkvHostObject::MmkvHostObject(const std::string& instanceId, std::string path,
-                               std::string cryptKey) {
+                               std::string cryptKey, MMKVMode mmkvMode) {
   bool hasEncryptionKey = cryptKey.size() > 0;
   __android_log_print(ANDROID_LOG_INFO, "RNMMKV",
                       "Creating MMKV instance \"%s\"... (Path: %s, Encrypted: %b)",
                       instanceId.c_str(), path.c_str(), hasEncryptionKey);
   std::string* pathPtr = path.size() > 0 ? &path : nullptr;
   std::string* cryptKeyPtr = cryptKey.size() > 0 ? &cryptKey : nullptr;
-  instance = MMKV::mmkvWithID(instanceId, mmkv::DEFAULT_MMAP_SIZE, MMKV_SINGLE_PROCESS, cryptKeyPtr,
-                              pathPtr);
+  instance = MMKV::mmkvWithID(instanceId, mmkv::DEFAULT_MMAP_SIZE, mmkvMode, cryptKeyPtr, pathPtr);
 
   if (instance == nullptr) {
     // Check if instanceId is invalid

android/src/main/cpp/MmkvHostObject.h

@@ -15,7 +15,8 @@ using namespace facebook;
 
 class JSI_EXPORT MmkvHostObject : public jsi::HostObject {
 public:
-  MmkvHostObject(const std::string& instanceId, std::string path, std::string cryptKey);
+  MmkvHostObject(const std::string& instanceId, std::string path, std::string cryptKey,
+                 MMKVMode mmkvMode);
 
 public:
   jsi::Value get(jsi::Runtime&, const jsi::PropNameID& name) override;

android/src/main/cpp/cpp-adapter.cpp

@@ -13,6 +13,18 @@ std::string getPropertyAsStringOrEmptyFromObject(jsi::Object& object,
   return value.isString() ? value.asString(runtime).utf8(runtime) : "";
 }
 
+const std::string MMKV_MULTI_PROCESS_MODE = "multi-process";
+MMKVMode getPropertyAsMMKVModeFromObject(jsi::Object& object, const std::string& propertyName,
+                                         jsi::Runtime& runtime) {
+  std::string value = getPropertyAsStringOrEmptyFromObject(object, propertyName, runtime);
+  if (value == MMKV_MULTI_PROCESS_MODE) {
+    return MMKV_MULTI_PROCESS;
+  }
+
+  // Use Single Process as default value
+  return MMKV_SINGLE_PROCESS;
+}
+
 void install(jsi::Runtime& jsiRuntime) {
   // MMKV.createNewInstance()
   auto mmkvCreateNewInstance = jsi::Function::createFromHostFunction(
@@ -28,8 +40,9 @@ void install(jsi::Runtime& jsiRuntime) {
         std::string path = getPropertyAsStringOrEmptyFromObject(config, "path", runtime);
         std::string encryptionKey =
             getPropertyAsStringOrEmptyFromObject(config, "encryptionKey", runtime);
+        MMKVMode mode = getPropertyAsMMKVModeFromObject(config, "mode", runtime);
 
-        auto instance = std::make_shared<MmkvHostObject>(instanceId, path, encryptionKey);
+        auto instance = std::make_shared<MmkvHostObject>(instanceId, path, encryptionKey, mode);
         return jsi::Object::createFromHostObject(runtime, instance);
       });
   jsiRuntime.global().setProperty(jsiRuntime, "mmkvCreateNewInstance",

example/ios/Podfile

@@ -10,6 +10,22 @@ if linkage != nil
   use_frameworks! :linkage => linkage.to_sym
 end
 
+def __apply_Xcode_14_3_RC_post_install_workaround(installer)
+  installer.pods_project.targets.each do |target|
+    target.build_configurations.each do |config|
+      config.build_settings['IPHONEOS_DEPLOYMENT_TARGET'] = '12.4'
+    end
+  end
+end
+
+def __apply_Xcode_15_0_RC_post_install_workaround(installer)
+  installer.pods_project.targets.each do |target|
+    target.build_configurations.each do |config|
+      config.build_settings['GCC_PREPROCESSOR_DEFINITIONS'] ||= ['$(inherited)', '_LIBCPP_ENABLE_CXX17_REMOVED_UNARY_BINARY_FUNCTION']
+    end
+  end
+end
+
 target 'MmkvExample' do
   config = use_native_modules!
 
@@ -42,5 +58,7 @@ target 'MmkvExample' do
       :mac_catalyst_enabled => false
     )
     __apply_Xcode_12_5_M1_post_install_workaround(installer)
+    __apply_Xcode_14_3_RC_post_install_workaround(installer)
+    __apply_Xcode_15_0_RC_post_install_workaround(installer)
   end
 end

ios/MmkvHostObject.h

@@ -16,7 +16,7 @@ using namespace facebook;
 
 class JSI_EXPORT MmkvHostObject : public jsi::HostObject {
 public:
-  MmkvHostObject(NSString* instanceId, NSString* path, NSString* cryptKey);
+  MmkvHostObject(NSString* instanceId, NSString* path, NSString* cryptKey, NSString* mode);
 
 public:
   jsi::Value get(jsi::Runtime&, const jsi::PropNameID& name) override;

ios/MmkvHostObject.mm

@@ -12,18 +12,25 @@
 #import <Foundation/Foundation.h>
 #import <vector>
 
-MmkvHostObject::MmkvHostObject(NSString* instanceId, NSString* path, NSString* cryptKey) {
+MmkvHostObject::MmkvHostObject(NSString* instanceId, NSString* path, NSString* cryptKey,
+                               NSString* mode) {
   NSData* cryptData = cryptKey == nil ? nil : [cryptKey dataUsingEncoding:NSUTF8StringEncoding];
 
   // Get appGroup value from info.plist using key "AppGroup"
   NSString* appGroup = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"AppGroup"];
-  if (appGroup == nil) {
+  if ([mode isEqualToString:@"single-process"]) {
+    if (appGroup != nil) {
+      NSLog(@"Warning: `mode` is set to 'single-process' but `appGroup` is also set in bundle! "
+            @"Ignoring `app groups` from bundle and using `mode` instead!");
+    }
     instance = [MMKV mmkvWithID:instanceId cryptKey:cryptData rootPath:path];
-  } else {
+  } else if (appGroup != nil) {
     if (path != nil) {
       NSLog(@"Warning: `path` is ignored when `appGroup` is set!");
     }
     instance = [MMKV mmkvWithID:instanceId cryptKey:cryptData mode:MMKVMultiProcess];
+  } else {
+    instance = [MMKV mmkvWithID:instanceId cryptKey:cryptData rootPath:path];
   }
 
   if (instance == nil) {

ios/MmkvModule.mm

@@ -50,24 +50,11 @@ + (NSString*)getPropertyAsStringOrNilFromObject:(jsi::Object&)object
   MMKVLogLevel logLevel = MMKVLogError;
 #endif
 
-  RCTUnsafeExecuteOnMainQueueSync(^{
-    // Get appGroup value from info.plist using key "AppGroup"
-    NSString* appGroup = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"AppGroup"];
-    if (appGroup == nil) {
-      [MMKV initializeMMKV:storageDirectory logLevel:logLevel];
-    } else {
-      NSString* groupDir = [[NSFileManager defaultManager]
-                               containerURLForSecurityApplicationGroupIdentifier:appGroup]
-                               .path;
-      [MMKV initializeMMKV:nil groupDir:groupDir logLevel:logLevel];
-    }
-  });
-
   // MMKV.createNewInstance()
   auto mmkvCreateNewInstance = jsi::Function::createFromHostFunction(
       runtime, jsi::PropNameID::forAscii(runtime, "mmkvCreateNewInstance"), 1,
-      [](jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* arguments,
-         size_t count) -> jsi::Value {
+      [=](jsi::Runtime& runtime, const jsi::Value& thisValue, const jsi::Value* arguments,
+          size_t count) -> jsi::Value {
         if (count != 1) {
           throw jsi::JSError(runtime, "MMKV.createNewInstance(..) expects one argument (object)!");
         }
@@ -82,8 +69,25 @@ + (NSString*)getPropertyAsStringOrNilFromObject:(jsi::Object&)object
         NSString* encryptionKey = [MmkvModule getPropertyAsStringOrNilFromObject:config
                                                                     propertyName:"encryptionKey"
                                                                          runtime:runtime];
+        NSString* mode = [MmkvModule getPropertyAsStringOrNilFromObject:config
+                                                           propertyName:"mode"
+                                                                runtime:runtime];
 
-        auto instance = std::make_shared<MmkvHostObject>(instanceId, path, encryptionKey);
+        RCTUnsafeExecuteOnMainQueueSync(^{
+          NSString* appGroup = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"AppGroup"];
+          if ([mode isEqualToString:@"single-process"]) {
+            [MMKV initializeMMKV:storageDirectory logLevel:logLevel];
+          } else if (appGroup != nil) {
+            NSString* groupDir = [[NSFileManager defaultManager]
+                                     containerURLForSecurityApplicationGroupIdentifier:appGroup]
+                                     .path;
+            [MMKV initializeMMKV:nil groupDir:groupDir logLevel:logLevel];
+          } else {
+            [MMKV initializeMMKV:storageDirectory logLevel:logLevel];
+          }
+        });
+
+        auto instance = std::make_shared<MmkvHostObject>(instanceId, path, encryptionKey, mode);
         return jsi::Object::createFromHostObject(runtime, instance);
       });
   runtime.global().setProperty(runtime, "mmkvCreateNewInstance", std::move(mmkvCreateNewInstance));

src/MMKV.ts

@@ -46,6 +46,21 @@ export interface MMKVConfiguration {
    * ```
    */
   encryptionKey?: string;
+  /**
+   * The MMKV mode. You can set its value to `multi-process` to support simultaneous read-write access between process at the cost of performance.
+   *
+   * This is useful when you want to share data between your react-native app and native extensions such as widgets.
+   *
+   * @example
+   * ```ts
+   * const extensionStorage = new MMKV({ id: 'mmkv.default', mode: 'multi-process' })
+   * ```
+   *
+   * _Notice_: on iOS additionally you need to set the AppGroup bundle property to share the same storage between your app and its extensions. If you don't set the AppGroup, the mode will be ignored and the mmkv will use the default storage location.
+   * More information on AppGroups [here](https://github.com/mrousavy/react-native-mmkv/tree/master#app-groups)
+   * _Notice_: for backward compatibility, the mode is set to `single-process` on android and for iOS it'll use `multi-process` if `AppGroup` exists.
+   */
+  mode?: 'single-process' | 'multi-process';
 }
 
 /**