Move snapshotsInSync to public (#3942)

Author: Brian Chen

Firestore/CHANGELOG.md

@@ -1,4 +1,7 @@
 # Unreleased
+- [feature] Added an `addSnapshotsInSyncListener()` method to
+  `FIRFirestore` that notifies you when all your snapshot listeners are
+  in sync with each other.
 
 # v1.5.1
 - [fixed] Fixed a memory access error discovered using the sanitizers in Xcode

Firestore/Source/API/FIRFirestore+Internal.h

@@ -15,7 +15,6 @@
  */
 
 #import "FIRFirestore.h"
-#import "FIRListenerRegistration.h"
 
 #include <memory>
 #include <string>
@@ -69,26 +68,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (const std::shared_ptr<util::AsyncQueue> &)workerQueue;
 
-/**
- * Attaches a listener for a snapshots-in-sync event. Server-generated
- * updates and local changes can affect multiple snapshot listeners.
- * The snapshots-in-sync event indicates that all listeners affected by
- * a given change have fired.
- *
- * NOTE: The snapshots-in-sync event only indicates that listeners are
- * in sync with each other, but does not relate to whether those
- * snapshots are in sync with the server. Use SnapshotMetadata in the
- * individual listeners to determine if a snapshot is from the cache or
- * the server.
- *
- * @param listener A callback to be called every time all snapshot
- * listeners are in sync with each other.
- * @return A FIRListenerRegistration object that can be used to remove the
- * listener.
- */
-- (id<FIRListenerRegistration>)addSnapshotsInSyncListener:(void (^)(void))listener
-    NS_SWIFT_NAME(addSnapshotsInSyncListener(_:));
-
 @property(nonatomic, assign, readonly) std::shared_ptr<api::Firestore> wrapped;
 
 @property(nonatomic, assign, readonly) const model::DatabaseId &databaseID;

Firestore/Source/Public/FIRFirestore.h

@@ -16,6 +16,8 @@
 
 #import <Foundation/Foundation.h>
 
+#import "FIRListenerRegistration.h"
+
 @class FIRApp;
 @class FIRCollectionReference;
 @class FIRDocumentReference;
@@ -208,6 +210,26 @@ NS_SWIFT_NAME(Firestore)
  */
 - (void)waitForPendingWritesWithCompletion:(void (^)(NSError *_Nullable error))completion;
 
+/**
+ * Attaches a listener for a snapshots-in-sync event. Server-generated
+ * updates and local changes can affect multiple snapshot listeners.
+ * The snapshots-in-sync event indicates that all listeners affected by
+ * a given change have fired.
+ *
+ * NOTE: The snapshots-in-sync event only indicates that listeners are
+ * in sync with each other, but does not relate to whether those
+ * snapshots are in sync with the server. Use SnapshotMetadata in the
+ * individual listeners to determine if a snapshot is from the cache or
+ * the server.
+ *
+ * @param listener A callback to be called every time all snapshot
+ * listeners are in sync with each other.
+ * @return A FIRListenerRegistration object that can be used to remove the
+ * listener.
+ */
+- (id<FIRListenerRegistration>)addSnapshotsInSyncListener:(void (^)(void))listener
+    NS_SWIFT_NAME(addSnapshotsInSyncListener(_:));
+
 #pragma mark - Terminating
 
 /**

Firestore/Swift/Tests/API/BasicCompileTests.swift

@@ -66,6 +66,8 @@ func main() {
 
   waitForPendingWrites(database: db)
 
+  addSnapshotsInSyncListener(database: db)
+
   terminateDb(database: db)
 }
 
@@ -462,6 +464,13 @@ func waitForPendingWrites(database db: Firestore) {
   }
 }
 
+func addSnapshotsInSyncListener(database db: Firestore) {
+  let listener = db.addSnapshotsInSyncListener {}
+
+  // Unsubscribe
+  listener.remove()
+}
+
 func terminateDb(database db: Firestore) {
   db.terminate { error in
     if let e = error {