Add the callback of send operation.

SocketRocket/SRWebSocket.h

@@ -59,6 +59,8 @@ extern NSString *const SRHTTPResponseErrorKey;
 
 @protocol SRWebSocketDelegate;
 
+typedef void (^SRSendCompletionBlock)(NSError * _Nullable error);
+
 ///--------------------------------------
 #pragma mark - SRWebSocket
 ///--------------------------------------
@@ -278,6 +280,17 @@ extern NSString *const SRHTTPResponseErrorKey;
  */
 - (BOOL)sendString:(NSString *)string error:(NSError **)error NS_SWIFT_NAME(send(string:));
 
+/**
+ Send a UTF-8 String to the server.
+
+ @param string     String to send.
+ @param completion The call back of send result.
+ If an error occurs, this block will invoked with an `NSError` object containing information about the error, otherwise this block will be invoked with `nil`.
+
+ @return `YES` if the string was scheduled to send, otherwise - `NO`.
+ */
+- (BOOL)sendString:(NSString *)string completion:(nullable SRSendCompletionBlock)completion NS_SWIFT_NAME(send(string:completion:));
+
 /**
  Send binary data to the server.
 
@@ -302,6 +315,17 @@ extern NSString *const SRHTTPResponseErrorKey;
  */
 - (BOOL)sendDataNoCopy:(nullable NSData *)data error:(NSError **)error NS_SWIFT_NAME(send(dataNoCopy:));
 
+/**
+ Send binary data to the server, without making a defensive copy of it first.
+
+ @param data       Data to send.
+ @param completion The call back of send result.
+ If an error occurs, this block will invoked with an `NSError` object containing information about the error, otherwise this block will be invoked with `nil`.
+
+ @return `YES` if the string was scheduled to send, otherwise - `NO`.
+ */
+- (BOOL)sendDataNoCopy:(nullable NSData *)data completion:(nullable SRSendCompletionBlock)completion NS_SWIFT_NAME(send(dataNoCopy:completion:));
+
 /**
  Send Ping message to the server with optional data.
 

SocketRocket/SRWebSocket.m

@@ -69,6 +69,31 @@
 NSString *const SRWebSocketErrorDomain = @"SRWebSocketErrorDomain";
 NSString *const SRHTTPResponseErrorKey = @"HTTPResponseStatusCode";
 
+@interface SRDataCallback : NSObject
+@property (nonatomic, assign) NSRange range;
+@property (nonatomic, copy, readonly) SRSendCompletionBlock completion;
+
++ (instancetype)new NS_UNAVAILABLE;
+- (instancetype)init NS_UNAVAILABLE;
+- (instancetype)initWithRange:(NSRange)range
+                   completion:(SRSendCompletionBlock)completion NS_DESIGNATED_INITIALIZER;
+
+@end
+
+@implementation SRDataCallback
+
+- (instancetype)initWithRange:(NSRange)range completion:(SRSendCompletionBlock)completion
+{
+    self = [super init];
+
+    _range = range;
+    _completion = [completion copy];
+
+    return self;
+}
+
+@end
+
 @interface SRWebSocket ()  <NSStreamDelegate>
 
 @property (atomic, assign, readwrite) SRReadyState readyState;
@@ -138,6 +163,8 @@ @implementation SRWebSocket {
 
     // proxy support
     SRProxyConnect *_proxyConnect;
+
+    NSMutableDictionary<NSValue *, SRDataCallback *> *_sendCallbacks;
 }
 
 @synthesize readyState = _readyState;
@@ -179,6 +206,8 @@ - (instancetype)initWithURLRequest:(NSURLRequest *)request protocols:(NSArray<NS
     _consumerPool = [[SRIOConsumerPool alloc] init];
 
     _scheduledRunloops = [[NSMutableSet alloc] init];
+
+    _sendCallbacks = [NSMutableDictionary dictionary];
 
     return self;
 }
@@ -548,6 +577,11 @@ - (void)_closeWithProtocolError:(NSString *)message;
 - (void)_failWithError:(NSError *)error;
 {
     dispatch_async(_workQueue, ^{
+        [_sendCallbacks enumerateKeysAndObjectsUsingBlock:^(NSValue * _Nonnull key, SRDataCallback * _Nonnull obj, BOOL * _Nonnull stop) {
+            obj.completion(error);
+        }];
+        [_sendCallbacks removeAllObjects];
+
         if (self.readyState != SR_CLOSED) {
             _failed = YES;
             [self.delegateController performDelegateBlock:^(id<SRWebSocketDelegate>  _Nullable delegate, SRDelegateAvailableMethods availableMethods) {
@@ -566,14 +600,30 @@ - (void)_failWithError:(NSError *)error;
     });
 }
 
-- (void)_writeData:(NSData *)data;
+- (void)_writeData:(NSData *)data
 {
-    [self assertOnWorkQueue];
+    [self _writeData:data completion:nil];
+}
 
+- (void)_writeData:(NSData *)data completion:(nullable SRSendCompletionBlock)completion
+{
+    [self assertOnWorkQueue];
+
     if (_closeWhenFinishedWriting) {
+        if (completion) {
+            completion(SRErrorWithCodeDescription(2134, @"socket is closed"));
+        }
         return;
     }
+
+    if (completion) {
+        NSUInteger location = dispatch_data_get_size(_outputBuffer);
+        NSRange dataRange = NSMakeRange(location, data.length);
+        SRDataCallback *record =  [[SRDataCallback alloc] initWithRange:dataRange completion:completion];
 
+        _sendCallbacks[[NSValue valueWithRange:dataRange]] = record;
+    }
+
     __block NSData *strongData = data;
     dispatch_data_t newData = dispatch_data_create(data.bytes, data.length, nil, ^{
         strongData = nil;
@@ -613,6 +663,24 @@ - (BOOL)sendString:(NSString *)string error:(NSError **)error
     return YES;
 }
 
+- (BOOL)sendString:(NSString *)string completion:(nullable SRSendCompletionBlock)completion
+{
+    if (self.readyState != SR_OPEN) {
+        NSString *message = @"Invalid State: Cannot call `sendString:completion:` until connection is open.";
+        if (completion) {
+            completion(SRErrorWithCodeDescription(2134, message));
+        }
+        SRDebugLog(message);
+        return NO;
+    }
+
+    string = [string copy];
+    dispatch_async(_workQueue, ^{
+        [self _sendFrameWithOpcode:SROpCodeTextFrame data:[string dataUsingEncoding:NSUTF8StringEncoding] completion:completion];
+    });
+    return YES;
+}
+
 - (BOOL)sendData:(nullable NSData *)data error:(NSError **)error
 {
     data = [data copy];
@@ -640,6 +708,27 @@ - (BOOL)sendDataNoCopy:(nullable NSData *)data error:(NSError **)error
     return YES;
 }
 
+- (BOOL)sendDataNoCopy:(nullable NSData *)data completion:(nullable SRSendCompletionBlock)completion
+{
+    if (self.readyState != SR_OPEN) {
+        NSString *message = @"Invalid State: Cannot call `sendDataNoCopy:completion:` until connection is open.";
+        if (completion) {
+            completion(SRErrorWithCodeDescription(2134, message));
+        }
+        SRDebugLog(message);
+        return NO;
+    }
+
+    dispatch_async(_workQueue, ^{
+        if (data) {
+            [self _sendFrameWithOpcode:SROpCodeBinaryFrame data:data completion:completion];
+        } else {
+            [self _sendFrameWithOpcode:SROpCodeTextFrame data:nil completion:completion];
+        }
+    });
+    return YES;
+}
+
 - (BOOL)sendPing:(nullable NSData *)data error:(NSError **)error
 {
     if (self.readyState != SR_OPEN) {
@@ -1060,7 +1149,27 @@ - (void)_pumpWriting;
 
         _outputBufferOffset += bytesWritten;
 
+        NSMutableArray<NSValue *> *removeKeys = [NSMutableArray array];
+        [_sendCallbacks enumerateKeysAndObjectsUsingBlock:^(NSValue * _Nonnull key, SRDataCallback * _Nonnull obj, BOOL * _Nonnull stop) {
+            if (NSMaxRange(obj.range) <= _outputBufferOffset) {
+                [removeKeys addObject:key];
+                obj.completion(nil);
+            }
+        }];
+        [_sendCallbacks removeObjectsForKeys:removeKeys];
+
         if (_outputBufferOffset > SRDefaultBufferSize() && _outputBufferOffset > dataLength / 2) {
+
+            NSArray<SRDataCallback *> *callbacks = _sendCallbacks.allValues;
+            [_sendCallbacks removeAllObjects];
+            [callbacks enumerateObjectsUsingBlock:^(SRDataCallback * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
+                NSRange dataRange = obj.range;
+                dataRange.location -= _outputBufferOffset;
+                obj.range = dataRange;
+                _sendCallbacks[[NSValue valueWithRange:dataRange]] = obj;
+            }];
+
+
             _outputBuffer = dispatch_data_create_subrange(_outputBuffer, _outputBufferOffset, dataLength - _outputBufferOffset);
             _outputBufferOffset = 0;
         }
@@ -1320,19 +1429,26 @@ -(void)_pumpScanner;
 
 static const size_t SRFrameHeaderOverhead = 32;
 
-- (void)_sendFrameWithOpcode:(SROpCode)opCode data:(NSData *)data
+- (void)_sendFrameWithOpcode:(SROpCode)opCode data:(NSData *)data completion:(nullable SRSendCompletionBlock)completion
 {
     [self assertOnWorkQueue];
 
     if (!data) {
+        if (completion) {
+            completion(nil);
+        }
         return;
     }
 
     size_t payloadLength = data.length;
 
     NSMutableData *frameData = [[NSMutableData alloc] initWithLength:payloadLength + SRFrameHeaderOverhead];
     if (!frameData) {
-        [self closeWithCode:SRStatusCodeMessageTooBig reason:@"Message too big"];
+        NSString *reason = @"Message too big";
+        [self closeWithCode:SRStatusCodeMessageTooBig reason:reason];
+        if (completion) {
+            completion(SRErrorWithCodeDescription(SRStatusCodeMessageTooBig, reason));
+        }
         return;
     }
     uint8_t *frameBuffer = (uint8_t *)frameData.mutableBytes;
@@ -1387,7 +1503,12 @@ - (void)_sendFrameWithOpcode:(SROpCode)opCode data:(NSData *)data
     assert(frameBufferSize <= frameData.length);
     frameData.length = frameBufferSize;
 
-    [self _writeData:frameData];
+    [self _writeData:frameData completion:completion];
+}
+
+- (void)_sendFrameWithOpcode:(SROpCode)opCode data:(NSData *)data
+{
+    [self _sendFrameWithOpcode:opCode data:data completion:nil];
 }
 
 - (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode