iOS: GCDAsyncSocket及其标签

Question

在我的应用程序中，我使用GCDAsyncSocket并以这种方式编写和阅读：

NSData *bufferWriteData = [NSData dataWithBytesNoCopy:bufferWrite length:17 freeWhenDone:YES];
[self.socket writeData:bufferWriteData withTimeout:-1 tag:1];
[self.socket readDataWithTimeout:-1 tag:1];

在读取委托方法后，数据：

- (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];
    }

在这个委托方法中，我回忆起"readDataWithTimeout“，因此以这种方式读取所有数据。

问题是当我打新电话时，如果是这样的话：

[self.socket writeData:bufferWriteData withTimeout:-1 tag:2];
[self.socket readDataWithTimeout:-1 tag:2];

我用tag =2启动一个新的写和一个新的读；当委托方法"didReadData“被调用时，我的代码进入标记=1的块中；它似乎不识别新的标记。

为什么会这样？

Answer 1

有几种方法可以解决这个问题。在您的例子中，最好的方法可能只是使用终止符来指示数据段的结束。你可以在上面读到：TCP是一个流。

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
    }