Implement GattClient#Disconnect for Apple implementation of BLEv2

PiperOrigin-RevId: 679218551

internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTClient.h

@@ -49,6 +49,14 @@ typedef void (^GNCGetCharacteristicCompletionHandler)(
 typedef void (^GNCReadCharacteristicValueCompletionHandler)(NSData *_Nullable value,
                                                             NSError *_Nullable error);
 
+/**
+ * A block to be invoked after a call to @c disconnect, requesting that the local connection to the
+ * remote peripheral be cancelled.
+ *
+ * @param peripheral The remote peripheral to disconnect from.
+ */
+typedef void (^GNCRequestDisconnectionHandler)(id<GNCPeripheral> peripheral);
+
 /**
  * An object that can be used to discover, explore, and interact with GATT services and
  * characteristics available on a remote peripheral.
@@ -64,8 +72,11 @@ typedef void (^GNCReadCharacteristicValueCompletionHandler)(NSData *_Nullable va
  * Initializes the GATT client with a specified peripheral.
  *
  * @param peripheral The peripheral instance.
+ * @param requestDisconnectionHandler Called on a private queue with @c peripheral when the
+ *                                    connection to the peripheral should be cancelled.
  */
-- (instancetype)initWithPeripheral:(id<GNCPeripheral>)peripheral;
+- (instancetype)initWithPeripheral:(id<GNCPeripheral>)peripheral
+       requestDisconnectionHandler:(GNCRequestDisconnectionHandler)requestDisconnectionHandler;
 
 /**
  * Discovers the specified characteristics of a service.
@@ -112,6 +123,9 @@ typedef void (^GNCReadCharacteristicValueCompletionHandler)(NSData *_Nullable va
                  completionHandler:
                      (nullable GNCReadCharacteristicValueCompletionHandler)completionHandler;
 
+/** Cancels an active or pending local connection to a peripheral. */
+- (void)disconnect;
+
 @end
 
 NS_ASSUME_NONNULL_END

internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEGATTClient.m

@@ -49,6 +49,7 @@ static NSError *AlreadyReadingCharacteristicError() {
 @implementation GNCBLEGATTClient {
   dispatch_queue_t _queue;
   id<GNCPeripheral> _peripheral;
+  GNCRequestDisconnectionHandler _requestDisconnectionHandler;
 
   /**
    * A map of service UUIDs with each service holding a map of a list of characterisitcs to a
@@ -70,15 +71,18 @@ static NSError *AlreadyReadingCharacteristicError() {
       *_readCharacteristicValueCompletionHandlers;
 }
 
-- (instancetype)initWithPeripheral:(id<GNCPeripheral>)peripheral {
-  return [self
-      initWithPeripheral:peripheral
-                   queue:dispatch_queue_create(kGNCBLEGATTClientQueueLabel, DISPATCH_QUEUE_SERIAL)];
+- (instancetype)initWithPeripheral:(id<GNCPeripheral>)peripheral
+       requestDisconnectionHandler:(GNCRequestDisconnectionHandler)requestDisconnectionHandler {
+  return [self initWithPeripheral:peripheral
+                            queue:dispatch_queue_create(kGNCBLEGATTClientQueueLabel,
+                                                        DISPATCH_QUEUE_SERIAL)
+      requestDisconnectionHandler:requestDisconnectionHandler];
 };
 
 // Private.
 - (instancetype)initWithPeripheral:(id<GNCPeripheral>)peripheral
-                             queue:(nullable dispatch_queue_t)queue {
+                             queue:(nullable dispatch_queue_t)queue
+       requestDisconnectionHandler:(GNCRequestDisconnectionHandler)requestDisconnectionHandler {
   self = [super init];
   if (self) {
     _queue = queue ?: dispatch_get_main_queue();
@@ -86,6 +90,7 @@ static NSError *AlreadyReadingCharacteristicError() {
     _peripheral.peripheralDelegate = self;
     _discoverCharacteristicsCompletionHandlers = [[NSMutableDictionary alloc] init];
     _readCharacteristicValueCompletionHandlers = [[NSMutableDictionary alloc] init];
+    _requestDisconnectionHandler = requestDisconnectionHandler;
   }
   return self;
 };
@@ -173,6 +178,12 @@ static NSError *AlreadyReadingCharacteristicError() {
   });
 }
 
+- (void)disconnect {
+  dispatch_async(_queue, ^{
+    _requestDisconnectionHandler(_peripheral);
+  });
+}
+
 #pragma mark - Internal
 
 - (CBCharacteristic *)synchronousCharacteristicWithUUID:(CBUUID *)characteristicUUID

internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEMedium.m

@@ -245,7 +245,13 @@ static NSError *AlreadyScanningError() {
   GNCGATTConnectionCompletionHandler handler = _connectionCompletionHandlers[peripheral.identifier];
   _connectionCompletionHandlers[peripheral.identifier] = nil;
   if (handler) {
-    GNCBLEGATTClient *client = [[GNCBLEGATTClient alloc] initWithPeripheral:peripheral];
+    GNCBLEGATTClient *client =
+        [[GNCBLEGATTClient alloc] initWithPeripheral:peripheral
+                         requestDisconnectionHandler:^(id<GNCPeripheral> peripheral) {
+                           dispatch_async(_queue, ^{
+                             [_centralManager cancelPeripheralConnection:peripheral];
+                           });
+                         }];
     handler(client, nil);
   }
 }

internal/platform/implementation/apple/Mediums/BLEv2/GNCCentralManager.h

@@ -79,6 +79,21 @@ NS_ASSUME_NONNULL_BEGIN
 - (void)connectPeripheral:(id<GNCPeripheral>)peripheral
                   options:(nullable NSDictionary<NSString *, id> *)options;
 
+/**
+ * Cancels an active or pending local connection to a peripheral.
+ *
+ * This method is nonblocking, and any @c CBPeripheral class commands that are still pending to
+ * @c peripheral may not complete. Because other apps may still have a connection to the peripheral,
+ * canceling a local connection doesn’t guarantee that the underlying physical link is immediately
+ * disconnected. From the app’s perspective, however, the peripheral is effectively disconnected,
+ * and the central manager object calls the @c centralManager:didDisconnectPeripheral:error: method
+ * of its delegate object.
+ *
+ * @param peripheral The peripheral to which the central manager is either trying to connect or has
+ * already connected.
+ */
+- (void)cancelPeripheralConnection:(id<GNCPeripheral>)peripheral;
+
 /** Asks the central manager to stop scanning for peripherals. */
 - (void)stopScan;