Having trouble programming streams

问题:

So here's the issue: The stream isn't writing at the right time and is unable to get a response from my server. I know I'm writing the right data, because when I stop the build, it writes to the server and the server is happy. I'm confused to as why this isn't happening at the right time.

I'm using GCDAsyncSocket to read/write to the socket

I've made a separate class to handle all networking, here's my code:

-(id)init{
    self = [super init];
    if (self) {
        asyncSocket = [[GCDAsyncSocket alloc] initWithDelegate:self         delegateQueue:dispatch_get_main_queue()];

        NSError *error = nil;
        if (![asyncSocket connectToHost:@"localhost" onPort:8888 error:&error]) //     Asynchronous!
        {
            // If there was an error, it's likely something like "already connected" or     "no delegate set"
            NSLog(@"I goofed: %@", error);
        }
    }
    return self;
}
//GCD Async Delegate Methods
- (void)socket:(GCDAsyncSocket *)sender didConnectToHost:(NSString *)host port:(UInt16)port
{
    NSLog(@"socket:%p didConnectToHost:%@ port:%hu", sender, host, port);
    NSLog(@"Cool, I'm connected! That was easy.");
}
 - (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag
{
    if (tag == 1)
        NSLog(@"First request sent");
    else if (tag == 2)
        NSLog(@"Second request sent");
    //read data of custom length
    /*
     if (tag == TAG_FIXED_LENGTH_HEADER)
     {
     int bodyLength = [self parseHeader:data];
     [socket readDataToLength:bodyLength withTimeout:-1 tag:TAG_RESPONSE_BODY];
     }
     else if (tag == TAG_RESPONSE_BODY)
     {
     // Process the response
     [self handleResponseBody:data];

     // Start reading the next response
     [socket readDataToLength:headerLength withTimeout:-1 tag:TAG_FIXED_LENGTH_HEADER];
     }
     */
}

-(void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag {
    NSError *error;
    serverJSONResponseParsed = [NSJSONSerialization JSONObjectWithData:data     options:kNilOptions error:&error];
}

-(BOOL)sendString:(NSString *)sendString{

    NSError *error;

    NSLog(@"Sending String: %@",sendString);

    NSDictionary *blobData = [NSDictionary dictionaryWithObjectsAndKeys:
                              sendString,@"string",
                              nil];
    NSString *blobString = [[NSString alloc]
                             initWithData:[NSJSONSerialization dataWithJSONObject:blobData      options:kNilOptions error:&error]
                             encoding:NSUTF8StringEncoding];
    NSLog(@"Blob Created: %@", blobString);
    NSDictionary *requestData = [NSDictionary dictionaryWithObjectsAndKeys:
                                 @"send_string",@"request_type",
                                  [NSNumber numberWithInt:0],@"security_level",
                                  @"ios",@"device_type",
                                  //No Email Provided, This is just for testing
                                 blobString,@"blob",
                                 nil];

    NSData *JSONRequestData = NULL;
    JSONRequestData = [NSJSONSerialization dataWithJSONObject:requestData options:kNilOptions error:&error];
            NSLog(@"Contents of JSONRequestData: %@",[[NSString alloc]     initWithData:JSONRequestData encoding:NSUTF8StringEncoding]);
     //Write the data
    [asyncSocket writeData:JSONRequestData withTimeout:-1 tag:1];

    //read a response
     [asyncSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:2];

    NSDictionary *JSONResponseData = serverJSONResponseParsed;
    /*
    if (serverResponse != NULL) {
         JSONResponseData = [NSJSONSerialization JSONObjectWithData:serverResponse      options:kNilOptions error:&error];
    }
     */
    NSString *failure = [JSONResponseData objectForKey:@"failure"];
    if ([failure respondsToSelector:@selector(isEqualToString:)]) {
        NSLog(@"Unknown Object, Not a NSString");
    }
     if ([failure isEqualToString:@"none"]) {
        NSLog(@"Success Sending String");
        return TRUE;
    }
    else {
        NSLog(@"%@",failure);
        return FALSE;
     }

}

Here's what the console says:

2012-08-16 18:15:27.831 FlokMobile[4257:c07] Sending String: hello
2012-08-16 18:15:27.832 FlokMobile[4257:c07] Blob Created: {"string":"hello"}
2012-08-16 18:15:27.832 FlokMobile[4257:c07] Contents of JSONRequestData:     {"security_level":0,"request_type":"send_string","device_type":"ios","blob":"     {\"string\":\"hello\"}"}
2012-08-16 18:15:27.833 FlokMobile[4257:c07] (null)
2012-08-16 18:15:27.833 FlokMobile[4257:c07] It didn't work - appdel
2012-08-16 18:15:27.850 FlokMobile[4257:c07] socket:0x6992890 didConnectToHost:127.0.0.1 port:8888
2012-08-16 18:15:27.850 FlokMobile[4257:c07] Cool, I'm connected! That was easy.
2012-08-16 18:15:27.851 FlokMobile[4257:c07] First request sent

回答1:

You are reading with this:      

[asyncSocket readDataToData:[GCDAsyncSocket CRLFData] withTimeout:-1 tag:2];

Which expects a CRLF as a separator of the stream. But I don't see where you append it to your JSONRequestData. So modifying your JSONRequestData to be mutable, like so:

NSMutableData *JSONRequestData;

And then before this line:

 

[asyncSocket writeData:JSONRequestData withTimeout:-1 tag:1];

Add this:

[JSONRequestData appendData:[GCDAsyncSocket CRLFData]];

回答2:

When sending short chunks of data always flush the buffer after each write which you want to have an immediate effect.
I don't see you doing that in your code.
If you don't do it then the buffer will be flushed only when it is full or the stream is closed.