在Swift开发过程中，确实能感觉到它的高效。不过虽然效率高但是有些功能还是借助C/C++来完成。所以学会Swift和C/C++交互还是必要的。下面以socket通讯库简单封装。
下面是客户端的c源码，阻塞之后连接好像有点问题，可能是我服务端没有处理这种机制。所以先不用阻塞的。

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// //  socket.c // //  Created by leehom on 16/2/16. //  Copyright © 2016年 lee.demo. All rights reserved. // #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <arpa inet.h=""> #include <sys types.h=""> #include <netinet in.h=""> #include <sys socket.h=""> #include <sys stat.h=""> #include <dirent.h> #include <netdb.h> #include <unistd.h> #include <fcntl.h> #include <signal.h> void _set_block(int socket,int on) {     int flags;     flags = fcntl(socket,F_GETFL,0);     if (on==0) {         fcntl(socket, F_SETFL, flags | O_NONBLOCK);     }else{         flags &= ~ O_NONBLOCK;         fcntl(socket, F_SETFL, flags);     } } int _connect(const char *host,int port,int timeout){     struct sockaddr_in sa;     struct hostent *hp;     int sockfd = -1;     hp = gethostbyname(host);     if(hp==NULL){         return -1;     }     bcopy((char *)hp->h_addr, (char *)&sa.sin_addr, hp->h_length);     sa.sin_family = hp->h_addrtype;     sa.sin_port = htons(port);     sockfd = socket(hp->h_addrtype, SOCK_STREAM, 0);     _set_block(sockfd,1);     int ret = connect(sockfd, (struct sockaddr *)&sa, sizeof(struct sockaddr));     if(ret == -1){         perror("连接失败\n");         exit(1);     }     fd_set          fdwrite;     struct timeval  tvSelect;     FD_ZERO(&fdwrite);     FD_SET(sockfd, &fdwrite);     tvSelect.tv_sec = timeout;     tvSelect.tv_usec = 0;     int retval = select(sockfd + 1,NULL, &fdwrite, NULL, &tvSelect);     if (retval<0) {         return -2;     }else if(retval==0){//timeout         return -3;     }else{         int error=0;         int errlen=sizeof(error);         getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &error, (socklen_t *)&errlen);         if(error!=0){             return -4;//connect fail         }         _set_block(sockfd, 1);         int set = 1;         setsockopt(sockfd, SOL_SOCKET, SO_NOSIGPIPE, (void *)&set, sizeof(int));         return sockfd;     } } int _close(int socketfd){     return close(socketfd); } int _read(int socketfd,char *data,int len){     int readlen=(int)read(socketfd,data,len);     return readlen; } int _write(int socketfd,const char *data,int len){     int byteswrite=0;     while (len-byteswrite>0) {         int writelen=(int)write(socketfd, data+byteswrite, len-byteswrite);         if (writelen<0) {             return -1;         }         byteswrite+=writelen;     }     return byteswrite; } //return socket fd int _listen(const char *addr,int port){     //create socket     int socketfd=socket(AF_INET, SOCK_STREAM, 0);     int reuseon   = 1;     setsockopt( socketfd, SOL_SOCKET, SO_REUSEADDR, &reuseon, sizeof(reuseon) );     //bind     struct sockaddr_in serv_addr;     memset( &serv_addr, '', sizeof(serv_addr));     serv_addr.sin_family = AF_INET;     serv_addr.sin_addr.s_addr = inet_addr(addr);     serv_addr.sin_port = htons(port);     int r=bind(socketfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr));     if(r==0){         if (listen(socketfd, 128)==0) {             return socketfd;         }else{             return -2;//listen error         }     }else{         return -1;//bind error     } } //return client socket fd int _accept(int onsocketfd,char *remoteip,int* remoteport){     socklen_t clilen;     struct sockaddr_in  cli_addr;     clilen = sizeof(cli_addr);     int newsockfd = accept(onsocketfd, (struct sockaddr *) &cli_addr, &clilen);     char *clientip=inet_ntoa(cli_addr.sin_addr);     memcpy(remoteip, clientip, strlen(clientip));     *remoteport=cli_addr.sin_port;     if(newsockfd>0){         return newsockfd;     }else{         return -1;     } } </signal.h></fcntl.h></unistd.h></netdb.h></dirent.h></sys></sys></netinet></sys></arpa></string.h></stdlib.h></stdio.h></errno.h>

然后就是Swift中封装接口和使用源码

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// //  main.swift // //  Created by leehom on 16/2/16. //  Copyright © 2016年 lee.demo. All rights reserved. // import Foundation @asmname("_set_block") func setBlock(socket:CInt,on:CInt) @asmname("_connect") func connect(host:UnsafePointer<cchar>,port:CInt,timeout:CInt)->CInt @asmname("_close") func close(socketfd:CInt)->CInt @asmname("_read") func read(socketfd:CInt,data:UnsafePointer<uint8>,len:CInt)->CInt @asmname("_write") func write(socketfd:CInt,data:UnsafePointer<cchar>,len:CInt)->CInt @asmname("_listen") func listener(addr:UnsafePointer<cchar>,port:CInt)->CInt @asmname("_accept") func accept(socketfd:CInt,remoteip:UnsafePointer<cchar>,remoteport:UnsafePointer<cint>)->CInt   let fd = connect("127.0.0.1", port: 3333, timeout: 15000) if(fd != 0){     //setBlock(fd, on: 0)//设置非阻塞     let bufLen:Int = 1024000     var buf:[UInt8] = [UInt8](count:bufLen,repeatedValue:0x0)     NSLog("开始读取数据...")     let actual:CInt = read(fd,data:&buf,len:CInt(bufLen))     if(actual > 0){         NSLog("实际读取字节:%i", actual)         let nString:String = NSString(bytes: buf, length: Int(actual), encoding: NSUTF8StringEncoding) as! String         print(nString)     }else{         NSLog("数据读取失败:%i", actual)     }     close(fd) } </cint></cchar></cchar></cchar></uint8></cchar>

输出的结果:

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