客户端：
导入头文件：
#import <sys/socket.h>
#import <netinet/in.h>
#import <arpa/inet.h>
#import <unistd.h>

1. 创建连接
CFSocketContext sockContext = {0, // 结构体的版本，必须为0
self,  // 一个任意指针的数据，可以用在创建时CFSocket对象相关联。这个指针被传递给所有的上下文中定义的回调。
NULL, // 一个定义在上面指针中的retain的回调， 可以为NULL
NULL, NULL};

CFSocketRef _socket = (kCFAllocatorDefault, // 为新对象分配内存，可以为nil
PF_INET, // 协议族，如果为0或者负数，则默认为PF_INET
SOCK_STREAM, // 套接字类型，如果协议族为PF_INET,则它会默认为SOCK_STREAM
IPPROTO_TCP, // 套接字协议，如果协议族是PF_INET且协议是0或者负数，它会默认为IPPROTO_TCP
kCFSocketConnectCallBack, // 触发回调函数的socket消息类型，具体见Callback Types
TCPServerConnectCallBack, // 上面情况下触发的回调函数
&sockContext // 一个持有CFSocket结构信息的对象，可以为nil
);

if (_socket != nil) {
    struct sockaddr_in addr4;   // IPV4
    memset(&addr4, 0, sizeof(addr4));
    addr4.sin_len = sizeof(addr4);
    addr4.sin_family = AF_INET;
    addr4.sin_port = htons(8888);
    addr4.sin_addr.s_addr = inet_addr([strAddress UTF8String]);  // 把字符串的地址转换为机器可识别的网络地址
       
    // 把sockaddr_in结构体中的地址转换为Data
    CFDataRef address = CFDataCreate(kCFAllocatorDefault, (UInt8 *)&addr4, sizeof(addr4));
    CFSocketConnectToAddress(_socket, // 连接的socket
address, // CFDataRef类型的包含上面socket的远程地址的对象
-1  // 连接超时时间，如果为负，则不尝试连接，而是把连接放在后台进行，如果_socket消息类型为kCFSocketConnectCallBack，将会在连接成功或失败的时候在后台触发回调函数
);

    CFRunLoopRef cRunRef = CFRunLoopGetCurrent();    // 获取当前线程的循环
    // 创建一个循环，但并没有真正加如到循环中，需要调用CFRunLoopAddSource
    CFRunLoopSourceRef sourceRef = CFSocketCreateRunLoopSource(kCFAllocatorDefault, _socket, 0);
    CFRunLoopAddSource(cRunRef, // 运行循环
    sourceRef,  // 增加的运行循环源, 它会被retain一次
    kCFRunLoopCommonModes  // 增加的运行循环源的模式
    );
    CFRelease(courceRef);
}

2. 设置回调函数
// socket回调函数的格式：
static void TCPServerConnectCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) ｛
    if (data != NULL) {
        // 当socket为kCFSocketConnectCallBack时，失败时回调失败会返回一个错误代码指针，其他情况返回NULL
        NSLog(@"连接失败");
        return;
    }
    TCPClient *client = (TCPClient *)info;
    // 读取接收的数据
    [info performSlectorInBackground:@selector(readStream) withObject:nil];
｝

3. 接收发送数据
// 读取接收的数据
- (void)readStream {
    char buffer[1024];
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    while (recv(CFSocketGetNative(_socket), //与本机关联的Socket 如果已经失效返回－1:INVALID_SOCKET
           buffer, sizeof(buffer), 0)) {
        NSLog(@"%@", [NSString stringWithUTF8String:buffer]);
    }
}

// 发送数据
- (void)sendMessage {
    NSString *stringTosend = @"你好";
    char *data = [stringTosend UTF8String];
    send(SFSocketGetNative(_socket), data, strlen(data) + 1, 0);
}


服务器端：

CFSockteRef _socket;
CFWriteStreamRef outputStream = NULL;

int setupSocket() {
    _socket = CFSocketCreate(kCFAllocatorDefault, PF_INET, SOCK_STREAM, IPPROTO_TCP, kCFSocketAcceptCallBack, TCPServerAcceptCallBack, NULL);
    if (NULL == _socket) {
        NSLog(@"Cannot create socket!");
        return 0;
    }
   
    int optval = 1;
    setsockopt(CFSocketGetNative(_socket), SOL_SOCKET, SO_REUSEADDR, // 允许重用本地地址和端口
(void *)&optval, sizeof(optval));
   
    struct sockaddr_in addr4;
    memset(&addr4, 0, sizeof(addr4));
    addr4.sin_len = sizeof(addr4);
    addr4.sin_family = AF_INET;
    addr4.sin_port = htons(port);
    addr4.sin_addr.s_addr = htonl(INADDR_ANY);
    CFDataRef address = CFDataCreate(kCFAllocatorDefault, (UInt8 *)&addr4, sizeof(addr4));
   
    if (kCFSocketSuccess != CFSocketSetAddress(_socket, address)) {
        NSLog(@"Bind to address failed!");
        if (_socket)
             CFRelease(_socket);
        _socket = NULL;
        return 0;
    }
       
    CFRunLoopRef cfRunLoop = CFRunLoopGetCurrent();
    CFRunLoopSourceRef source = CFSocketCreateRunLoopSource(kCFAllocatorDefault, _socket, 0);
    CFRunLoopAddSource(cfRunLoop, source, kCFRunLoopCommonModes);
    CFRelease(source);
   
    return 1;
}

// socket回调函数，同客户端
void TCPServerAcceptCallBack(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) {
    if (kCFSocketAcceptCallBack == type) {
        // 本地套接字句柄
        CFSocketNativeHandle nativeSocketHandle = *(CFSocketNativeHandle *)data;
        uint8_t name[SOCK_MAXADDRLEN];      
        socklen_t nameLen = sizeof(name);
        if (0 != getpeername(nativeSocketHandle, (struct sockaddr *)name, &nameLen)) {
            NSLog(@"error");
            exit(1);
        }
        NSLog(@"%@ connected.", inet_ntoa( ((struct sockaddr_in *)name)->sin_addr )):

        CFReadStreamRef iStream;
        CFWriteStreamRef oStream;
        // 创建一个可读写的socket连接
        CFStreamCreatePairWithSocket(kCFAllocatorDefault, nativeSocketHandle, &iStream, &oStream); 
        if (iStream && oStream) {
            CFStreamClientContext streamContext = {0, NULL, NULL, NULL};
            if (!CFReadStreamSetClient(iStream, kCFStreamEventHasBytesAvaiable,
                                       readStream, // 回调函数，当有可读的数据时调用
                                       &streamContext)){
                exit(1);
            }

            if (!CFReadStreamSetClient(iStream, kCFStreamEventCanAcceptBytes, writeStream, &streamContext)){
                exit(1);
            }

            CFReadStreamScheduleWithRunLoop(iStream, CFRunLoopGetCurrent(), kCFRunLoopCommomModes);
            CFWriteStreamScheduleWithRunLoop(wStream, CFRunLoopGetCurrent(), kCFRunLoopCommomModes);
            CFReadStreamOpen(iStream);
            CFWriteStreamOpen(wStream);
        } else {
             close(nativeSocketHandle); 
        }
    }
}

// 读取数据
void readStream(CFReadStreamRef stream, CFStreamEventType eventType, void *clientCallBackInfo) {
    UInt8 buff[255];
    CFReadStreamRead(stream, buff, 255);
    printf("received: %s", buff);
}

void writeStream (CFWriteStreamRef stream, CFStreamEventType eventType, void *clientCallBackInfo) {
    outputStream = stream;
}

main {
    char *str = "nihao";
   
    if (outputStream != NULL) {
        CFWriteStreamWrite(outputStream, str, strlen(line) + 1);
    } else {
        NSLog(@"Cannot send data!");
    }
}

// 开辟一个线程线程函数中
void runLoopInThread() {
    int res = setupSocket();
    if (!res) {
        exit(1);
    }
    CFRunLoopRun();    // 运行当前线程的CFRunLoop对象
}

本文转自 卓行天下  51CTO博客，原文链接：http://blog.51cto.com/9951038/1787766，如需转载请自行联系原作者