iOS：使用CFStreamCreatePairWithSocketToHost的套接字网络基础

我正在使用套接字使用CFStreamCreatePairWithSocketToHost()发送和接收数据,并试图在发送多组数据(即不仅仅是1个请求)时如何完成此操作.

问题

目前我可以发送数据并接收响应(即1次往返).但是,在我发送outputStream中的所有数据后,流被关闭(即接收NsstreamEventEndEncountered).

题

所以问题是,当我想发送多个数据请求时会发生什么？

>每次要发送新数据对象时,是否设置了新套接字？
>我是否必须重置outputStream并发送更多数据.

码

大部分代码来自Cocoa Streams Documentation：

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view,typically from a nib.

    _data = [[NSMutableData alloc] init];
    [self initNetworkCommunication];

    [self sendString:@"Hello World!"];
}

- (void)initNetworkCommunication {
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;

    CFStreamCreatePairWithSocketToHost(NULL,(CFStringRef)@"123.456.0.0",1234,&readStream,&writeStream);

    inputStream = (NSInputStream *)readStream; // ivar
    [inputStream setDelegate:self];
    [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [inputStream open];

    outputStream = (NSOutputStream *)writeStream; // ivar
    [outputStream setDelegate:self];
    [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [outputStream open];
}

- (void)sendString:(Nsstring *)string {
    NSData *data = [[NSData alloc] initWithData:[string dataUsingEncoding:NSASCIIStringEncoding]];
    [_data appendData:data];
    [data release];
}

- (void)stream:(Nsstream *)theStream handleEvent:(NsstreamEvent)streamEvent {
    NSLog(@"stream event %u",streamEvent);

    switch (streamEvent) {
        case NsstreamEventOpenCompleted:
            NSLog(@"Stream opened");
            break;
        case NsstreamEventHasspaceAvailable: {
            uint8_t *readBytes = (uint8_t *)[_data mutableBytes];
            readBytes += byteIndex; // ivar
            int data_len = [_data length];
            unsigned int len = ((data_len - byteIndex >= 1024) ? 1024 : (data_len - byteIndex));
            uint8_t buf[len];
            (void)memcpy(buf,readBytes,len);
            len = [(NSOutputStream *)theStream write:(const uint8_t *)buf maxLength:len];
            NSLog(@"Sending buffer of len: %d",len);
            byteIndex += len;
            break;
        }
        case NsstreamEventHasBytesAvailable:
            if (theStream == inputStream) {
                uint8_t buffer[1024];
                int len;

                while ([inputStream hasBytesAvailable]) {
                    len = [inputStream read:buffer maxLength:sizeof(buffer)];
                    if (len > 0) {
                        Nsstring *output = [[Nsstring alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

                        if (nil != output) {
                            NSLog(@"server said: %@",output);
                        }
                    }
                }

                [self sendString:@"Another Test"];
            }
            break;
        case NsstreamEventErrorOccurred:
            NSLog(@"Can not connect to the host!");
            break;
        case NsstreamEventEndEncountered:
            NSLog(@"Closing stream...");
            [theStream close];
            [theStream removeFromrunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
            [theStream release];
            theStream = nil;
            break;
        default:
            NSLog(@"UnkNown event");
    }
}

响应：

2012-08-15 08:16:30.896 Sockets[34836:f803] Opened input stream.
2012-08-15 08:16:30.898 Sockets[34836:f803] Opened output stream.
2012-08-15 08:16:30.899 Sockets[34836:f803] Sending buffer of len: 12
2012-08-15 08:16:30.900 Sockets[34836:f803] Sending buffer of len: 0
2012-08-15 08:16:30.901 Sockets[34836:f803] Closing output stream.
2012-08-15 08:16:30.939 Sockets[34836:f803] server said: Hello World!

请注意,在发送数据后,outputStream流将关闭.我尝试在[self sendString：@“Another Test”]之前重新启动outputStream.我也试过了idz的回答.

根据文档,我相信len：0的发送缓冲区是我的问题.

If the delegate receives an NsstreamEventHasspaceAvailable event and
does not write anything to the stream,it does not receive further
space-available events from the run loop until the NSOutputStream
object receives more bytes. When this happens,the run loop is
restarted for space-available events.

但是,文档没有说明在到达流末尾时关闭流.所以我很困惑……