Prepare macos application group setting

objectbox/README.md

@@ -69,6 +69,20 @@ dev_dependencies:
 
 * Install the packages: `flutter pub get`
 * XCode/iOS only: increase the deployment target to iOS 11 and, under Architectures, replace `${ARCHS_STANDARD}` with `arm64` (or `$ARCHS_STANDARD_64_BIT`). See [FAQ](#faq) for details.
+* If targeting macOS (creating sandboxed macOS apps): you need to specify an application group.
+  Check all `macos/Runner/*.entitlements` files if they contain a `<dict>` section with correct group ID info. 
+  Change the string value to the `DEVELOPMENT_TEAM` you can find in your Xcode settings, plus an application-specific suffix, for example: 
+
+  ```xml
+  <key>com.apple.security.application-groups</key>
+  <array>
+    <string>FGDTDLOBXDJ.demo</string>
+  </array>
+  ```
+
+  Next, in your app code, pass the same string when opening the Store, for example: `Store(getObjectBoxModel(), directory: ..., macosApplicationGroup: 'FGDTDLOBXDJ.demo')`.  
+  Note: Pick a short group identifier; there's an internal limit in macOS that requires the complete string to be 
+  19 characters or fewer.
 * Sync + Android only: in your `android/app/build.gradle` set `minSdkVersion 21` in section `android -> defaultConfig`. 
 
 ### Dart Native

objectbox/example/flutter/objectbox_demo/lib/main.dart

@@ -50,8 +50,10 @@ class ViewModel {
   late final Stream<Query<Note>> _queryStream;
 
   ViewModel(Directory dir)
-      : _store =
-            Store(getObjectBoxModel(), directory: dir.path + '/objectbox') {
+      : _store = Store(getObjectBoxModel(),
+            directory: dir.path + '/objectbox',
+            macosApplicationGroup: 'objectbox.demo' // replace with a real name
+            ) {
     _box = Box<Note>(_store);
     final qBuilder = _box.query()..order(Note_.date, flags: Order.descending);
     _queryStream = qBuilder.watch(triggerImmediately: true);

objectbox/example/flutter/objectbox_demo/macos/Runner/DebugProfile.entitlements

@@ -8,5 +8,9 @@
 	<true/>
 	<key>com.apple.security.network.server</key>
 	<true/>
+  <key>com.apple.security.application-groups</key>
+  <array>
+    <string>objectbox.demo</string>
+  </array>
 </dict>
 </plist>

objectbox/example/flutter/objectbox_demo/macos/Runner/Release.entitlements

@@ -4,5 +4,9 @@
 <dict>
 	<key>com.apple.security.app-sandbox</key>
 	<true/>
+  <key>com.apple.security.application-groups</key>
+  <array>
+    <string>objectbox.demo</string>
+  </array>
 </dict>
 </plist>

objectbox/example/flutter/objectbox_demo_sync/lib/main.dart

@@ -52,7 +52,9 @@ class ViewModel {
 
   ViewModel(Directory dir)
       : _store = Store(getObjectBoxModel(),
-            directory: dir.path + '/objectbox-sync') {
+            directory: dir.path + '/objectbox',
+            macosApplicationGroup: 'objectbox.demo' // replace with a real name
+            ) {
     _box = Box<Note>(_store);
     final qBuilder = _box.query()..order(Note_.date, flags: Order.descending);
     _queryStream = qBuilder.watch(triggerImmediately: true);

objectbox/example/flutter/objectbox_demo_sync/macos/Runner/DebugProfile.entitlements

@@ -8,5 +8,9 @@
 	<true/>
 	<key>com.apple.security.network.server</key>
 	<true/>
+  <key>com.apple.security.application-groups</key>
+  <array>
+    <string>objectbox.demo</string>
+  </array>
 </dict>
 </plist>

objectbox/example/flutter/objectbox_demo_sync/macos/Runner/Release.entitlements

@@ -4,5 +4,9 @@
 <dict>
 	<key>com.apple.security.app-sandbox</key>
 	<true/>
+  <key>com.apple.security.application-groups</key>
+  <array>
+    <string>objectbox.demo</string>
+  </array>
 </dict>
 </plist>

objectbox/lib/src/native/store.dart

@@ -71,14 +71,30 @@ class Store {
       int? maxDBSizeInKB,
       int? fileMode,
       int? maxReaders,
-      bool queriesCaseSensitiveDefault = true})
+      bool queriesCaseSensitiveDefault = true,
+      String? macosApplicationGroup})
       : _weak = false,
         _queriesCaseSensitiveDefault = queriesCaseSensitiveDefault,
         _dbDir = path.context.canonicalize(
             (directory == null || directory.isEmpty)
                 ? 'objectbox'
                 : directory) {
     try {
+      if (Platform.isMacOS && macosApplicationGroup != null) {
+        if (!macosApplicationGroup.endsWith('/')) {
+          macosApplicationGroup += '/';
+        }
+        if (macosApplicationGroup.length > 20) {
+          ArgumentError.value(macosApplicationGroup, 'macosApplicationGroup',
+              'Must be at most 20 characters long');
+        }
+        final cStr = macosApplicationGroup.toNativeUtf8();
+        try {
+          C.posix_sem_prefix_set(cStr.cast());
+        } finally {
+          malloc.free(cStr);
+        }
+      }
       if (_openStoreDirectories.contains(_dbDir)) {
         throw UnsupportedError(
             'Cannot create multiple Store instances for the same directory. '