RCOCOA-2334: Move initial subscription logic into Core

CHANGELOG.md

@@ -2,6 +2,7 @@ x.y.z Release notes (yyyy-MM-dd)
 =============================================================
 ### Enhancements
 * The default base url in `AppConfiguration` has been updated to point to `services.cloud.mongodb.com`. See https://www.mongodb.com/docs/atlas/app-services/domain-migration/ for more information. ([#8512](https://github.com/realm/realm-swift/issues/8512))
+* Added `SyncConfiguration.initialSubscriptions` which describes the initial subscription configuration that was passed when constructing the `SyncConfiguration`. ([#8548](https://github.com/realm/realm-swift/issues/8548))
 
 ### Fixed
 * <How to hit and notice issue? what was the impact?> ([#????](https://github.com/realm/realm-swift/issues/????), since v?.?.?)

Package.swift

@@ -244,6 +244,7 @@ let package = Package(
                 "Realm/RLMEmailPasswordAuth.mm",
                 "Realm/RLMFindOneAndModifyOptions.mm",
                 "Realm/RLMFindOptions.mm",
+                "Realm/RLMInitialSubscriptionsConfiguration.m",
                 "Realm/RLMMongoClient.mm",
                 "Realm/RLMMongoCollection.mm",
                 "Realm/RLMNetworkTransport.mm",

Realm.podspec

@@ -55,6 +55,7 @@ Pod::Spec.new do |s|
                               'include/RLMApp.h',
                               'include/RLMAppCredentials.h',
                               'include/RLMBSON.h',
+                              'include/RLMInitialSubscriptionsConfiguration.h',
                               'include/RLMNetworkTransport.h',
                               'include/RLMPushClient.h',
                               'include/RLMProviderClient.h',

Realm.xcodeproj/project.pbxproj

@@ -53,9 +53,12 @@
 		0C3BD4B325C1BDF1007CFDD3 /* RLMDictionary.mm in Sources */ = {isa = PBXBuildFile; fileRef = 0C3BD4B125C1BDF1007CFDD3 /* RLMDictionary.mm */; };
 		0C3BD4D325C1C5AB007CFDD3 /* Map.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0C3BD4D225C1C5AB007CFDD3 /* Map.swift */; };
 		0C5796A225643D7500744CAE /* RLMUUID.mm in Sources */ = {isa = PBXBuildFile; fileRef = 0C57969F25643D7500744CAE /* RLMUUID.mm */; };
+		0C63BB902BCD787300E25C3A /* RLMInitialSubscriptionsConfiguration.h in Sources */ = {isa = PBXBuildFile; fileRef = 0CC270AB2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h */; };
 		0C86B33925E15B6000775FED /* PrimitiveDictionaryPropertyTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 0C86B33825E15B6000775FED /* PrimitiveDictionaryPropertyTests.m */; };
 		0C9758BF264974660097B48D /* SwiftRLMDictionaryTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0C9758BE264974660097B48D /* SwiftRLMDictionaryTests.swift */; };
 		0CBF2DB927286FFD00635902 /* ProjectedCollectTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0CBF2DB827286FFD00635902 /* ProjectedCollectTests.swift */; };
+		0CC270AA2BCD664200788EE1 /* RLMInitialSubscriptionsConfiguration.m in Sources */ = {isa = PBXBuildFile; fileRef = 0CC270A92BCD664200788EE1 /* RLMInitialSubscriptionsConfiguration.m */; };
+		0CC270AC2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h in Headers */ = {isa = PBXBuildFile; fileRef = 0CC270AB2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		0CD1632826D3DF1D0027C49B /* ProjectionTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0CD1632726D3DF1C0027C49B /* ProjectionTests.swift */; };
 		0CED6DB82655087200B80277 /* RLMDictionary_Private.h in Headers */ = {isa = PBXBuildFile; fileRef = 0C3BD50125C1DE6F007CFDD3 /* RLMDictionary_Private.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		1A0512771D8746CD00806AEC /* RLMSyncConfiguration.h in Headers */ = {isa = PBXBuildFile; fileRef = 1A3623651D8384BA00945A54 /* RLMSyncConfiguration.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -628,6 +631,8 @@
 		0C86B33825E15B6000775FED /* PrimitiveDictionaryPropertyTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = PrimitiveDictionaryPropertyTests.m; sourceTree = "<group>"; };
 		0C9758BE264974660097B48D /* SwiftRLMDictionaryTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SwiftRLMDictionaryTests.swift; sourceTree = "<group>"; };
 		0CBF2DB827286FFD00635902 /* ProjectedCollectTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProjectedCollectTests.swift; sourceTree = "<group>"; };
+		0CC270A92BCD664200788EE1 /* RLMInitialSubscriptionsConfiguration.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RLMInitialSubscriptionsConfiguration.m; sourceTree = "<group>"; };
+		0CC270AB2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RLMInitialSubscriptionsConfiguration.h; sourceTree = "<group>"; };
 		0CD1632526D3DD7B0027C49B /* Projection.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Projection.swift; sourceTree = "<group>"; };
 		0CD1632726D3DF1C0027C49B /* ProjectionTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ProjectionTests.swift; sourceTree = "<group>"; };
 		1A0512731D87413000806AEC /* RLMSyncUtil_Private.hpp */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.h; path = RLMSyncUtil_Private.hpp; sourceTree = "<group>"; };
@@ -1200,6 +1205,8 @@
 				4993220324129DCD00A0EC8E /* RLMCredentials.h */,
 				4993220424129DCD00A0EC8E /* RLMCredentials.mm */,
 				4993220224129DCD00A0EC8E /* RLMCredentials_Private.hpp */,
+				0CC270AB2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h */,
+				0CC270A92BCD664200788EE1 /* RLMInitialSubscriptionsConfiguration.m */,
 				4993221524129E6600A0EC8E /* RLMNetworkTransport.h */,
 				4993221424129E6500A0EC8E /* RLMNetworkTransport.mm */,
 				CF330BBB24E56E3A00F07EE2 /* RLMNetworkTransport_Private.hpp */,
@@ -1906,6 +1913,7 @@
 				6807E64F2487F9210096066F /* RLMPushClient_Private.hpp in Headers */,
 				1AD397CF1F72FFC7002AA897 /* RLMRealm+Sync.h in Headers */,
 				5D659EBF1BE04556006515A0 /* RLMRealm.h in Headers */,
+				0CC270AC2BCD665800788EE1 /* RLMInitialSubscriptionsConfiguration.h in Headers */,
 				5D659EC01BE04556006515A0 /* RLMRealm_Dynamic.h in Headers */,
 				5D659EC11BE04556006515A0 /* RLMRealm_Private.h in Headers */,
 				5D659EC21BE04556006515A0 /* RLMRealmConfiguration.h in Headers */,
@@ -2454,6 +2462,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				0C63BB902BCD787300E25C3A /* RLMInitialSubscriptionsConfiguration.h in Sources */,
 				3F73BC961E3A878500FE80B6 /* NSError+RLMSync.m in Sources */,
 				5D659E851BE04556006515A0 /* RLMAccessor.mm in Sources */,
 				5D659E861BE04556006515A0 /* RLMAnalytics.mm in Sources */,
@@ -2513,6 +2522,7 @@
 				531F956C27906F7600E497F1 /* RLMSyncSubscription.mm in Sources */,
 				1A84132F1D4BCCE600C5326F /* RLMSyncUtil.mm in Sources */,
 				3F67DB3E1E26D69C0024533D /* RLMThreadSafeReference.mm in Sources */,
+				0CC270AA2BCD664200788EE1 /* RLMInitialSubscriptionsConfiguration.m in Sources */,
 				5D659E9A1BE04556006515A0 /* RLMUpdateChecker.mm in Sources */,
 				CF76F7DD24816AAB00890DD2 /* RLMUpdateResult.mm in Sources */,
 				1ABDCDB01D793008003489E3 /* RLMUser.mm in Sources */,

Realm/ObjectServerTests/AsyncSyncTests.swift

@@ -20,7 +20,7 @@
 
 import Realm
 import Realm.Private
 import RealmSwift
 import XCTest
 
 #if canImport(RealmTestSupport)
@@ -263,7 +263,7 @@
 
         let configuration = try configuration()
         func isolatedOpen(_ actor: isolated CustomExecutorActor) async throws {
             _ = try await Realm(configuration: configuration, actor: actor, downloadBeforeOpen: .always)
         }
 
         // Try opening the Realm with the Task being cancelled at every possible
@@ -406,7 +406,7 @@
             ["favourite_colour": "green", "apples": 10]
         ])
 
         try await user.refreshCustomData()
         XCTAssertEqual(user.customData["favourite_colour"], .string("green"))
         XCTAssertEqual(user.customData["apples"], .int64(10))
     }
@@ -611,6 +611,11 @@
             })
         })
         config.objectTypes = [SwiftPerson.self]
+
+        XCTAssertNotNil(config.syncConfiguration?.initialSubscriptions)
+        XCTAssertNotNil(config.syncConfiguration?.initialSubscriptions?.callback)
+        XCTAssertEqual(config.syncConfiguration?.initialSubscriptions?.rerunOnOpen, false)
+
         let realm = try await Realm(configuration: config, downloadBeforeOpen: .once)
         XCTAssertEqual(realm.subscriptions.count, 1)
         checkCount(expected: 10, realm, SwiftPerson.self)
@@ -644,6 +649,11 @@
             }
         }, rerunOnOpen: true)
         config.objectTypes = [SwiftPerson.self]
+
+        XCTAssertNotNil(config.syncConfiguration?.initialSubscriptions)
+        XCTAssertNotNil(config.syncConfiguration?.initialSubscriptions?.callback)
+        XCTAssertEqual(config.syncConfiguration?.initialSubscriptions?.rerunOnOpen, false)
+
         try await Task {
             let realm = try await Realm(configuration: config, downloadBeforeOpen: .once)
             XCTAssertEqual(realm.subscriptions.count, 1)
@@ -784,7 +794,7 @@
             _ = try await results0.subscribe()
             ex.fulfill()
         }
         await fulfillment(of: [ex], timeout: 1.0)
         try await task.value
         XCTAssertEqual(realm.subscriptions.count, 1)
     }
@@ -807,7 +817,7 @@
             XCTAssertEqual(realm.subscriptions.count, 1)
             ex.fulfill()
         }
         await fulfillment(of: [ex], timeout: 5.0)
         XCTAssertEqual(realm.subscriptions.count, 1)
     }
 
@@ -849,7 +859,7 @@
         let user = try await createUser()
         var config = user.flexibleSyncConfiguration()
         config.objectTypes = [SwiftPerson.self]
         let realm = try await Realm(configuration: config, actor: MainActor.shared)
         let results1 = try await realm.objects(SwiftPerson.self)
             .where { $0.firstName == name && $0.age > 8 }.subscribe(waitForSync: .onCreation)
         XCTAssertEqual(results1.count, 2)
@@ -869,7 +879,7 @@
         let user = try await createUser()
         var config = user.flexibleSyncConfiguration()
         config.objectTypes = [SwiftPerson.self]
         let realm = try await Realm(configuration: config, actor: CustomGlobalActor.shared)
         let results1 = try await realm.objects(SwiftPerson.self)
             .where { $0.firstName == name && $0.age > 8 }.subscribe(waitForSync: .onCreation)
         XCTAssertEqual(results1.count, 2)
@@ -1037,7 +1047,7 @@
             XCTAssertEqual(realm.subscriptions.count, 1)
             expectation.fulfill()
         }
         await fulfillment(of: [expectation], timeout: 2.0)
         try await task.value
     }
 
@@ -1084,7 +1094,7 @@
             XCTAssertEqual(realm.subscriptions.count, 1)
             expectation.fulfill()
         }
         await fulfillment(of: [expectation], timeout: 1)
     }
 
     @MainActor

Realm/RLMInitialSubscriptionsConfiguration.h

@@ -0,0 +1,70 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2024 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+
+#import <Foundation/Foundation.h>
+#import <Realm/RLMRealm.h>
+
+RLM_HEADER_AUDIT_BEGIN(nullability, sendability)
+
+/**
+ A block which receives a subscription set instance, that can be used to add an initial set of subscriptions which will be executed
+ when the Realm is first opened.
+ */
+RLM_SWIFT_SENDABLE
+typedef void(^RLMFlexibleSyncInitialSubscriptionsBlock)(RLMSyncSubscriptionSet * _Nonnull subscriptions);
+
+/**
+ A configuration controlling how the initial subscriptions are populated when a Realm file is first opened.
+
+ @see `RLMSubscriptionSet`
+ */
+@interface RLMInitialSubscriptionsConfiguration : NSObject
+
+/**
+ A callback that's executed in an update block to populate the initial subscriptions for that Realm.
+
+ This callback will only be executed when the Realm is first created, unless `rerunOnOpen` is `true`, in which case it will be executed every time
+ the Realm is opened.
+ */
+@property (nonatomic, readonly) RLMFlexibleSyncInitialSubscriptionsBlock callback;
+
+/**
+ Controls whether to re-run the `callback` every time the Realm is opened.
+ */
+@property (nonatomic, readonly) BOOL rerunOnOpen;
+
+/**
+ Create a new initial subscriptions configuration.
+
+ @param callback Callback that will be invoked to update the subscriptions for this Realm file when it's first created or every time it's opened if `rerunOnOpen` is `true`.
+ @param rerunOnOpen A flag controlling whether to run the subscription callback every time the Realm is opened or only the first time.
+ */
+- (instancetype)initWithCallback:(RLMFlexibleSyncInitialSubscriptionsBlock)callback rerunOnOpen: (BOOL)rerunOnOpen;
+
+
+/**
+ Create a new initial subscriptions configuration.
+
+ @param callback Callback that will be invoked to update the subscriptions for this Realm file when it's first created.
+ */
+- (instancetype)initWithCallback:(RLMFlexibleSyncInitialSubscriptionsBlock)callback;
+
+@end
+
+RLM_HEADER_AUDIT_END(nullability, sendability)

Realm/RLMInitialSubscriptionsConfiguration.m

@@ -0,0 +1,36 @@
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2024 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+
+#import "RLMInitialSubscriptionsConfiguration.h"
+
+@implementation RLMInitialSubscriptionsConfiguration
+
+-(id)initWithCallback:(RLMFlexibleSyncInitialSubscriptionsBlock)callback
+{
+    return [self initWithCallback: callback rerunOnOpen: false];
+}
+
+-(id)initWithCallback:(RLMFlexibleSyncInitialSubscriptionsBlock)callback rerunOnOpen: (BOOL)rerunOnOpen
+{
+    _callback = callback;
+    _rerunOnOpen = rerunOnOpen;
+    return self;
+}
+
+@end

Realm/RLMRealm.mm

@@ -447,7 +447,6 @@ + (instancetype)realmWithConfiguration:(RLMRealmConfiguration *)configuration
         }
     }
 
-    bool isFirstOpen = false;
     if (realm->_schema) { }
     else if (dynamic) {
         realm->_schema = [RLMSchema dynamicSchemaFromObjectStoreSchema:realm->_realm->schema()];
@@ -482,16 +481,9 @@ + (instancetype)realmWithConfiguration:(RLMRealmConfiguration *)configuration
             };
         }
 
-        DataInitializationFunction initializationFunction;
-        if (!configuration.rerunOnOpen && configuration.initialSubscriptions) {
-            initializationFunction = [&isFirstOpen](SharedRealm) {
-                isFirstOpen = true;
-            };
-        }
-
         try {
             realm->_realm->update_schema(schema.objectStoreCopy, config.schema_version,
-                                         std::move(migrationFunction), std::move(initializationFunction));
+                                         std::move(migrationFunction));
         }
         catch (...) {
             RLMRealmTranslateException(error);
@@ -522,15 +514,6 @@ + (instancetype)realmWithConfiguration:(RLMRealmConfiguration *)configuration
         realm->_realm->m_binding_context->realm = realm->_realm;
     }
 
-#if REALM_ENABLE_SYNC
-    if (isFirstOpen || (configuration.rerunOnOpen && !realmIsCached)) {
-        RLMSyncSubscriptionSet *subscriptions = realm.subscriptions;
-        [subscriptions update:^{
-            configuration.initialSubscriptions(subscriptions);
-        }];
-    }
-#endif
-
     // Run Analytics and Update checker, this will be run only the first any realm open
     [self runFirstCheckForConfiguration:configuration schema:realm.schema];
 

Realm/RLMRealmConfiguration.h

@@ -34,13 +34,6 @@ RLM_HEADER_AUDIT_BEGIN(nullability, sendability)
 RLM_SWIFT_SENDABLE
 typedef BOOL (^RLMShouldCompactOnLaunchBlock)(NSUInteger totalBytes, NSUInteger bytesUsed);
 
-/**
- A block which receives a subscription set instance, that can be used to add an initial set of subscriptions which will be executed
- when the Realm is first opened.
- */
-RLM_SWIFT_SENDABLE
-typedef void(^RLMFlexibleSyncInitialSubscriptionsBlock)(RLMSyncSubscriptionSet * _Nonnull subscriptions);
-
 /**
  An `RLMRealmConfiguration` instance describes the different options used to
  create an instance of a Realm.

Realm/RLMRealmConfiguration.mm

@@ -130,8 +130,6 @@ - (instancetype)copyWithZone:(NSZone *)zone {
     configuration->_customSchema = _customSchema;
     configuration->_eventConfiguration = _eventConfiguration;
     configuration->_migrationObjectClass = _migrationObjectClass;
-    configuration->_initialSubscriptions = _initialSubscriptions;
-    configuration->_rerunOnOpen = _rerunOnOpen;
     return configuration;
 }
 

Realm/RLMRealmConfiguration_Private.h

@@ -33,10 +33,6 @@ RLM_HEADER_AUDIT_BEGIN(nullability)
 @property (nonatomic, nullable) Class migrationObjectClass;
 @property (nonatomic) bool disableAutomaticChangeNotifications;
 
-// Flexible Sync
-@property (nonatomic, readwrite, nullable) RLMFlexibleSyncInitialSubscriptionsBlock initialSubscriptions;
-@property (nonatomic, readwrite) BOOL rerunOnOpen;
-
 // Get the default configuration without copying it
 + (RLMRealmConfiguration *)rawDefaultConfiguration;
 

Realm/RLMSyncConfiguration.h

@@ -19,11 +19,13 @@
 #import <Foundation/Foundation.h>
 
 #import <Realm/RLMSyncManager.h>
+#import <Realm/RLMInitialSubscriptionsConfiguration.h>
 
 @class RLMApp;
 @class RLMRealm;
 @class RLMRealmConfiguration;
 @class RLMUser;
+@class RLMInitialSubscriptionsConfiguration;
 @protocol RLMBSON;
 
 RLM_HEADER_AUDIT_BEGIN(nullability, sendability)
@@ -175,6 +177,11 @@ typedef void(^RLMClientResetAfterBlock)(RLMRealm * _Nonnull beforeFrozen, RLMRea
  */
 @property (nonatomic, nullable) RLMSyncErrorReportingBlock manualClientResetHandler;
 
+/**
+ A configuration that controls how initial subscriptions are populated when the Realm is opened.
+ @see `RLMInitialSubscriptionsConfiguration`
+ */
+@property (nonatomic, readwrite, nullable) RLMInitialSubscriptionsConfiguration *initialSubscriptions;
 
 /**
  Whether nonfatal connection errors should cancel async opens.

Realm/RLMSyncConfiguration.mm

@@ -21,13 +21,15 @@
 #import "RLMApp_Private.hpp"
 #import "RLMBSON_Private.hpp"
 #import "RLMError_Private.hpp"
+#import "RLMInitialSubscriptionsConfiguration.h"
 #import "RLMRealm_Private.hpp"
 #import "RLMRealmConfiguration_Private.h"
 #import "RLMRealmConfiguration_Private.hpp"
 #import "RLMRealmUtil.hpp"
 #import "RLMSchema_Private.hpp"
 #import "RLMSyncManager_Private.hpp"
 #import "RLMSyncSession_Private.hpp"
+#import "RLMSyncSubscription.h"
 #import "RLMSyncUtil_Private.hpp"
 #import "RLMUser_Private.hpp"
 #import "RLMUtil.hpp"
@@ -80,6 +82,23 @@ void operator()(std::shared_ptr<Realm> local, ThreadSafeReference remote, bool)
         }
     }
 };
+
+struct InitialSubscriptionsWrapper : CallbackSchema {
+    RLMFlexibleSyncInitialSubscriptionsBlock block;
+    void operator()(std::shared_ptr<Realm> local) {
+        @autoreleasepool {
+            RLMRealm *realm = [RLMRealm realmWithSharedRealm:local
+                                                      schema:customSchema
+                                                     dynamic:dynamic
+                                                      freeze:false];
+
+            RLMSyncSubscriptionSet* subscriptions = realm.subscriptions;
+            [subscriptions update:^{
+                block(subscriptions);
+            }];
+        }
+    }
+};
 } // anonymous namespace
 
 @interface RLMSyncConfiguration () {
@@ -190,6 +209,26 @@ - (void)setManualClientResetHandler:(RLMSyncErrorReportingBlock)manualClientRese
     [self assignConfigErrorHandler:self.user];
 }
 
+- (RLMInitialSubscriptionsConfiguration *)initialSubscriptions {
+    if (_config->subscription_initializer) {
+        auto wrapper = _config->subscription_initializer.target<InitialSubscriptionsWrapper>();
+
+        return [[RLMInitialSubscriptionsConfiguration alloc] initWithCallback: wrapper->block
+                                                                  rerunOnOpen: _config->rerun_init_subscription_on_open];
+    }
+
+    return nil;
+}
+
+- (void)setInitialSubscriptions:(RLMInitialSubscriptionsConfiguration *)initialSubscriptions {
+    if (initialSubscriptions) {
+        _config->subscription_initializer = InitialSubscriptionsWrapper{.block = initialSubscriptions.callback};
+        _config->rerun_init_subscription_on_open = initialSubscriptions.rerunOnOpen;
+    } else {
+        _config->subscription_initializer = nil;
+    }
+}
+
 void RLMSetConfigInfoForClientResetCallbacks(realm::SyncConfig& syncConfig, RLMRealmConfiguration *config) {
     if (syncConfig.notify_before_client_reset) {
         auto before = syncConfig.notify_before_client_reset.target<BeforeClientResetWrapper>();
@@ -201,6 +240,11 @@ void RLMSetConfigInfoForClientResetCallbacks(realm::SyncConfig& syncConfig, RLMR
         after->dynamic = config.dynamic;
         after->customSchema = config.customSchema;
     }
+    if (syncConfig.subscription_initializer) {
+        auto initializer = syncConfig.subscription_initializer.target<InitialSubscriptionsWrapper>();
+        initializer->dynamic = config.dynamic;
+        initializer->customSchema = config.customSchema;
+    }
 }
 
 - (id<RLMBSON>)partitionValue {