iOS: GCDAsyncSocket and its tag - ios

Question

In my app I'm using GCDAsyncSocket and I write and read in this way:
NSData *bufferWriteData = [NSData dataWithBytesNoCopy:bufferWrite length:17 freeWhenDone:YES];
[self.socket writeData:bufferWriteData withTimeout:-1 tag:1];
[self.socket readDataWithTimeout:-1 tag:1];
after I read in the delegate method the data:
- (void) socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
NSLog(#"did read data");
if (tag == 1){
//analyze my data...
[self.socket readDataWithTimeout:-1 tag:1];
}
inside this delegate method I recall the "readDataWithTimeout" so in this way I read all data.
The problem id when I do a new call, if I do:
[self.socket writeData:bufferWriteData withTimeout:-1 tag:2];
[self.socket readDataWithTimeout:-1 tag:2];
I start a new write and a new read with tag = 2;
When the delegate method "didReadData" is called my code enter inside the block of tag = 1; it seems that it don't recognize the new tag.
Why it happen?

Answer 1

There are several ways to handle this. In your case, the best way probably just used a terminator to indicate the end of that data segment. You can read up there: TCP is a stream.
NSData *MyCommandTerminator(void)
{
return [NSData dataWithBytes:"\x0D\x0A\x0B\x0A" length:4];
}
//callback from Asyncsocket for incoming data
- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag //sender and receiver
{
NSLog(#"GCDAsyncSocket didreaddata");
// do what you wish with data and read again using a terminator
[sock readDataToData:MyCommandTerminator() withTimeout:-1 tag:1]; //tag is not being used here
}
// your method to send data
-(void)sendData:(NSData *)data
{
// NSData *bufferWriteData = [NSData dataWithBytesNoCopy:bufferWrite length:17 freeWhenDone:YES];
NSLog(#"Sendata wehere _peerSocket is your instance of GCDAsyncSocket");
NSMutableData *myData = [[NSMutableData alloc] initWithData:data];
[myData appendData:MyCommandTerminator()];
[_peerSocket writeData:myData withTimeout:-1 tag:2]; // tag is not being used here
}