iOS

1、BSDSocket

一套 unix 系统下的 socket API（纯 C）。
iOS 系统基于 unix，所以支持底层的 BSD Socket，在 Xcode 中可以直接使用。

2、基本使用

2.1 Client 客户端

TCP 客户端

包含头文件

	#import <sys/socket.h>
	#import <netinet/in.h>
	#import <arpa/inet.h>
	#import <ifaddrs.h>

创建 Socket

	// client Socket
	@property (nonatomic, assign) int clientSocket;
	
	self.clientSocket = socket(AF_INET, SOCK_STREAM, 0);
	    
	if (self.clientSocket > 0) {
	    NSLog(@"Socket 创建成功 %d", self.clientSocket);
	} else {
	    NSLog(@"Socket 创建失败");
	}

连接到服务器

	// 创建服务器地址结构体
	struct sockaddr_in serverAddress;
	bzero(&serverAddress, sizeof(serverAddress));
	serverAddress.sin_family      = AF_INET;                        // 协议族
	serverAddress.sin_port        = htons(12345);                   // 端口 端口数据高位在前低位在后 12345 ＝> 3039 => 3930
	serverAddress.sin_addr.s_addr = inet_addr("192.168.88.100");    // inet_addr 函数可以把 ip 地址转换成一个整数
	    
	int isConnected = connect(self.clientSocket, (const struct sockaddr *)&serverAddress, sizeof(serverAddress));
	    
	if (isConnected) {
	    NSLog(@"连接失败 %d", isConnected);
	} else {
	    NSLog(@"连接成功");
	}

发送数据

	NSString *message = @"你好";
	    
	ssize_t sendLen = send(self.clientSocket, message.UTF8String, strlen(message.UTF8String), 0);
	    
	if (sendLen > 0) {
	    NSLog(@"发送成功，发送 %ld 个字节数据", sendLen);
	} else {
	    NSLog(@"发送失败 %zd", sendLen);
	}

接收数据

	// 接收字符串的数组，typedef unsigned char uint8_t;
	uint8_t buffer[1024];
	    
	ssize_t recvLen = recv(self.clientSocket, buffer, sizeof(buffer), 0);
	    
	if (recvLen > 0) {
	    
	    // 按照服务器返回的长度，从 buffer 中，读取二进制数据，建立 NSData 对象
	    NSData *data = [NSData dataWithBytes:buffer length:recvLen];
	    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
	    
	    NSLog(@"接收成功，接收到 %ld 个字节数据
 接收到：%@", recvLen, str);
	} else {
	    NSLog(@"接收失败 %zd", recvLen);
	}

关闭连接

	// 数据传递完毕之后，关闭连接
	int isCloseed = close(self.clientSocket);
	    
	NSLog(@"%d", isCloseed);

2.2 Server 服务端

TCP 服务端

包含头文件

	#import <sys/socket.h>
	#import <netinet/in.h>
	#import <arpa/inet.h>
	#import <ifaddrs.h>

创建 Socket

	// server Socket
	@property (nonatomic, assign) int serverSocket;
	
	// client Socket
	@property (nonatomic, assign) int clientSocket;

	self.serverSocket = socket(AF_INET, SOCK_STREAM, 0);
	    
	if (self.serverSocket > 0) {
	    NSLog(@"Socket 创建成功 %d", self.serverSocket);
	} else {
	    NSLog(@"Socket 创建失败");
	}

开始监听

	// 创建服务器地址结构体
	struct sockaddr_in serverAddress;
	bzero(&serverAddress, sizeof(serverAddress));
	serverAddress.sin_family      = AF_INET;
	serverAddress.sin_port        = htons(12345);
	serverAddress.sin_addr.s_addr = inet_addr("192.168.88.100");
	    
	int isBind = bind(self.serverSocket, (const struct sockaddr *)&serverAddress, sizeof(serverAddress));
	    
	if (isBind) {
	    NSLog(@"绑定失败 %d", isBind);
	    return;
	} else {
	    NSLog(@"绑定成功");
	}
	    
	int isListen = listen(self.serverSocket, 10);
	    
	if (isListen) {
	    NSLog(@"监听失败 %d", isListen);
	    return;
	} else {
	    NSLog(@"监听成功");
	}
	    
	// clientSocket
	struct sockaddr_in clientAddress;
	bzero(&clientAddress, sizeof(clientAddress));
	socklen_t len = sizeof(clientAddress);
	
	self.clientSocket = accept(self.serverSocket, (struct sockaddr *)&clientAddress, &len);
	    
	if (self.clientSocket) {
	    NSLog(@"接收成功 %d，client IP：%zd", self.clientSocket, clientAddress);
	} else {
	    NSLog(@"接收失败");
	}

发送数据

	NSString *message = @"你好";
	    
	// 使用 clientSocket
	ssize_t sendLen = send(self.clientSocket, message.UTF8String, strlen(message.UTF8String), 0);
	    
	if (sendLen > 0) {
	    NSLog(@"发送成功，发送 %ld 个字节数据", sendLen);
	} else {
	    NSLog(@"发送失败 %zd", sendLen);
	}

接收数据

	// 接收字符串的数组，typedef unsigned char uint8_t;
	uint8_t buffer[1024];
	    
	// 使用 clientSocket
	ssize_t recvLen = recv(self.clientSocket, buffer, sizeof(buffer), 0);
	    
	if (recvLen > 0) {
	    
	    // 按照服务器返回的长度，从 buffer 中，读取二进制数据，建立 NSData 对象
	    NSData *data = [NSData dataWithBytes:buffer length:recvLen];
	    NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
	    
	    NSLog(@"接收成功，接收到 %ld 个字节数据
 接收到：%@", recvLen, str);
	} else {
	    NSLog(@"接收失败 %zd", recvLen);
	}

关闭连接

	// 数据传递完毕之后，关闭连接
	int isCloseed = close(self.serverSocket);
	    
	NSLog(@"%d", isCloseed);

3、网络访问

1、请求：
- 1）请求行
  - GET / HTTP/1.1
  - 方法 GET
  - 路径 /
  - 协议 HTTP 1.1
- 2）请求头
  - Host: localhost 主机
  - User-Agent: 告诉服务器客户端的类型
  - Accept: 告诉服务器客户端支持的格式
  - Accept-Language: 告诉服务器客户端的语言
  - Accept-Encoding: 告诉服务器客户端支持的压缩格式
2、响应：
- 1）状态行
  - HTTP/1.1 200 OK
    - 协议 HTTP 1.1
    - 状态码:
      - 200 成功
      - 404 页面没找到
      - 301 内容没变化，用在缓存
- 2）响应头(主要在开发下载应用的时候使用的)
  - Date: Tue, 24 Mar 2015 01:52:25 GMT 访问日期
  - Server: Apache/2.4.9 (Unix) 访问服务器的类型
  - Content-Location: index.html.en 访问的文件名
  - Content-Length: 45 访问文件的大小
  - Content-Type: text/html 访问文件的类型
- 3）数据实体
  - <html><body><h1>It works!</h1></body></html>
  - 访问服务器最需的，相当于 NSURLConnection 异步方法回调中的 data。

TCP 客户端

	// 包含头文件
	#import <sys/socket.h>
	#import <netinet/in.h>
	#import <arpa/inet.h>
	#import <ifaddrs.h>
	
	@property (nonatomic, assign) int clientSocket;
	
	- (void)socketHttpRequest {
    
    	// 连接到服务器，80 端口 apache 中就是 http 的协议
    	if (![self connection:@"127.0.0.1" port:80]) {                                              
        	return;
    	}
  	
  		// 创建请求
    	NSString *requestStr = @"GET / HTTP/1.1
"                                                  
    	"Host: localhost
"
    	"User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:36.0) Gecko/20100101 Firefox/36.0
"
    	"Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
"
    	"Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3
"
    	
    	// 
 拼接换行，内容由 firefox 浏览器的网络控制面板的原始请求头信息中复制
    	"Accept-Encoding: gzip, deflate
"                                                          
    	
    	// 删除最后三行，最后一行加两个 


    	"Connection: keep-alive

";                                                               
    
    	// 发送接收请求，发送给 web 服务器的请求需要遵守 http 协议
    	NSString *recvStr = [self sendAndRecv:requestStr];                                          
    
    	NSLog(@"%@", recvStr);
	}

	/// 创建连接
	- (BOOL)connection:(NSString *)hostText port:(int)port {
    
    	// 创建 Socket

        	self.clientSocket = socket(AF_INET, SOCK_STREAM, 0);
    
    	// 连接到服务器

        	struct sockaddr_in serverAddress;
        	bzero(&serverAddress, sizeof(serverAddress));
        	serverAddress.sin_family      = AF_INET;
        	serverAddress.sin_port        = htons(port);
        	serverAddress.sin_addr.s_addr = inet_addr(hostText.UTF8String);

        	int isConnected = connect(self.clientSocket, (const struct sockaddr *)&serverAddress, sizeof(serverAddress));
    
        	return (isConnected == 0);
	}

	/// 发送和接收字符串
	- (NSString *)sendAndRecv:(NSString *)message {
    
    	// 发送数据

        	send(self.clientSocket, message.UTF8String, strlen(message.UTF8String), 0);
    
    	// 接收数据
    	
        	uint8_t buffer[1024];                                                                  	

        	ssize_t recvLen = recv(self.clientSocket, buffer, sizeof(buffer), 0);
    
        	NSData *data = [NSData dataWithBytes:buffer length:recvLen];                           	
        	NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

        	return str;
	}

4、客户端使用

TCP 客户端 & UDP

	// 包含头文件
	#import <sys/socket.h>
	#import <netinet/in.h>
	#import <arpa/inet.h>
	#import <ifaddrs.h>
	
	typedef NS_ENUM (NSInteger,ServerType) {
	    ServerTypeTCP,
	    ServerTypeUDP
	};
	
	@property (weak, nonatomic) IBOutlet UITextField *desIPTF;
	@property (weak, nonatomic) IBOutlet UITextField *desPortTF;
	
	@property (weak, nonatomic) IBOutlet UITextField *locIPTF;
	@property (weak, nonatomic) IBOutlet UITextField *locPortTF;
	
	@property (weak, nonatomic) IBOutlet UITextView *recvTextView;
	@property (weak, nonatomic) IBOutlet UITextField *sendTF;
	
	@property (nonatomic, assign) int clientSockfd;
	@property (nonatomic, assign) int udpSockfd;
	
	@property (nonatomic, assign) ServerType serType;
	
	- (void)viewDidLoad {
	    [super viewDidLoad];
	    
	    NSString *ip_addr = [self getIPAddress];
	    _locIPTF.text = ip_addr;
	}
	
	#pragma mark - 创建 TCP 连接
	
	- (IBAction)connectTCPServer:(id)sender {
	    
	    [NSThread detachNewThreadSelector:@selector(connectTCPSer) toTarget:self withObject:nil];
	}
	
	- (void)connectTCPSer {
	    
	    self.serType = ServerTypeTCP;
	    
	    BOOL success;
	    int err;
	    
	    // 创建 socket
	    self.clientSockfd = socket(AF_INET, SOCK_STREAM, 0);
	    success = (self.clientSockfd != -1);
	    
	    NSString *logStr = nil;
	    
	    if (success == NO) {
	        
	        logStr = @"创建 socket 失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"创建 socket 成功...
";
	        [self showMessage:logStr];
	        
	        // 服务器地址
	        struct sockaddr_in ser_addr;
	        memset(&ser_addr, 0, sizeof(ser_addr));
	        ser_addr.sin_len         = sizeof(ser_addr);
	        ser_addr.sin_family      = AF_INET;
	        ser_addr.sin_port        = htons(_desPortTF.text.intValue);
	        ser_addr.sin_addr.s_addr = inet_addr(_desIPTF.text.UTF8String);
	        
	        // 连接
	        err = connect(self.clientSockfd, (struct sockaddr *)&ser_addr, sizeof(ser_addr));
	        success = (err == 0);
	    }
	    
	    if (success == NO) {
	        
	        logStr = @"socket 连接失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = [NSString stringWithFormat:@"socket 连接 %@ 成功...
", _desIPTF.text];
	        [self showMessage:logStr];
	        
	        char buf[1024];
	        do {
	            // 接收数据
	            ssize_t recvLen = recv(self.clientSockfd, buf, sizeof(buf), 0);
	            
	            if (recvLen > 0) {
	                logStr = [NSString stringWithFormat:@"recv：%@
", [NSString stringWithUTF8String:buf]];
	                [self showMessage:logStr];
	            }
	            
	        } while (strcmp(buf, "exit") != 0);
	    }
	}
	
	#pragma mark - 创建 UDP 连接
	
	- (IBAction)connectUDP:(id)sender {
	    
	    [NSThread detachNewThreadSelector:@selector(connectUDP) toTarget:self withObject:nil];
	}
	
	- (void)connectUDP {
	    
	    self.serType = ServerTypeUDP;
	    
	    BOOL success;
	    int err;
	    
	    // 创建 Socket
	    self.udpSockfd = socket(AF_INET, SOCK_DGRAM, 0);
	    success = (self.udpSockfd != -1);
	    
	    NSString *logStr = nil;
	    
	    if (success == NO) {
	        
	        logStr = @"创建 socket 失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"创建 socket 成功...
";
	        [self showMessage:logStr];
	        
	        // 本地地址
	        struct sockaddr_in loc_addr;
	        bzero(&loc_addr, sizeof(loc_addr));
	        loc_addr.sin_port        = htons(_locPortTF.text.intValue);
	        loc_addr.sin_addr.s_addr = inet_addr(_locIPTF.text.UTF8String);
	        
	        // 绑定
	        err = bind(self.udpSockfd, (const struct sockaddr *)&loc_addr, sizeof(loc_addr));
	        success = (err == 0);
	    }
	    
	    if (success == NO) {
	        
	        logStr = @"socket 绑定失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"socket 绑定成功...
";
	        [self showMessage:logStr];
	        
	        // 目标地址
	        struct sockaddr_in des_addr;
	        bzero(&des_addr, sizeof(des_addr));
	        des_addr.sin_family      = AF_INET;
	        des_addr.sin_port        = htons(_desPortTF.text.intValue);
	        des_addr.sin_addr.s_addr = inet_addr(_desIPTF.text.UTF8String);
	        
	        char buf[256];
	        bzero(buf, sizeof(buf));
	        
	        while(1) {
	            
	            // 接收数据
	            socklen_t des_addr_len = sizeof(des_addr);
	            ssize_t recvLen = recvfrom(self.udpSockfd, buf, sizeof(buf), 0, (struct sockaddr*)&des_addr, &des_addr_len);
	            
	            if (recvLen > 0) {
	                logStr = [NSString stringWithFormat:@"recv：%@
", [NSString stringWithUTF8String:buf]];
	                [self showMessage:logStr];
	            }
	        }
	    }
	}
	
	#pragma mark - 发送数据
	
	- (IBAction)btnClick:(id)sender {
	    
	    if (_sendTF.text.length == 0) {
	        return;
	    } else {
	        
	        ssize_t sendLen;
	        
	        if (self.serType == ServerTypeTCP) {
	            
	            // 发送数据
	            sendLen = send(self.clientSockfd, _sendTF.text.UTF8String, strlen(_sendTF.text.UTF8String), 0);
	            
	        } else if (self.serType == ServerTypeUDP) {
	            
	            // 目标地址
	            struct sockaddr_in des_addr;
	            bzero(&des_addr, sizeof(des_addr));
	            des_addr.sin_family      = AF_INET;
	            des_addr.sin_port        = htons(_desPortTF.text.intValue);
	            des_addr.sin_addr.s_addr = inet_addr(_desIPTF.text.UTF8String);
	            
	            // 发送数据
	            sendLen = sendto(self.udpSockfd, _sendTF.text.UTF8String, strlen(_sendTF.text.UTF8String), 0, 
	                             (struct sockaddr *)&des_addr, sizeof(des_addr));
	        }
	        
	        if (sendLen > 0) {
	            NSString *logStr = [NSString stringWithFormat:@"send：%@
", _sendTF.text];
	            [self showMessage:logStr];
	        }
	    }
	}
	
	#pragma mark - 获取本地 IP 地址
	
	- (NSString *)getIPAddress {
	    
	    NSString *address = @"error";
	    struct ifaddrs *interfaces = NULL;
	    struct ifaddrs *temp_addr = NULL;
	    int success = 0;
	    
	    // retrieve the current interfaces - returns 0 on success
	    success = getifaddrs(&interfaces);
	    
	    if (success == 0) {
	        
	        // Loop through linked list of interfaces
	        temp_addr = interfaces;
	        
	        while (temp_addr != NULL) {
	            
	            if (temp_addr->ifa_addr->sa_family == AF_INET) {
	                
	                // Check if interface is en0 which is the wifi connection on the iPhone
	                if ([[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"en0"]) {
	                    
	                    // Get NSString from C String
	                    address = [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)temp_addr->ifa_addr)->sin_addr)];
	                }
	            }
	            temp_addr = temp_addr->ifa_next;
	        }
	    }
	    
	    // Free memory
	    freeifaddrs(interfaces);
	    return address;
	}
	
	// 显示信息
	- (void)showMessage:(NSString *)msg {
	    
	    dispatch_async(dispatch_get_main_queue(), ^{
	        
	        _recvTextView.text = [_recvTextView.text stringByAppendingString:msg];
	    });
	}

Socket5 Socket6

5、服务端使用

TCP 服务端 & UDP

	// 包含头文件
	#import <sys/socket.h>
	#import <netinet/in.h>
	#import <arpa/inet.h>
	#import <ifaddrs.h>
	
	typedef NS_ENUM (NSInteger,ServerType) {
	    ServerTypeTCP,
	    ServerTypeUDP
	};
	
	@property (weak, nonatomic) IBOutlet UITextField *desIPTF;
	@property (weak, nonatomic) IBOutlet UITextField *desPortTF;
	
	@property (weak, nonatomic) IBOutlet UITextField *locIPTF;
	@property (weak, nonatomic) IBOutlet UITextField *locPortTF;
	
	@property (weak, nonatomic) IBOutlet UITextView *recvTextView;
	@property (weak, nonatomic) IBOutlet UITextField *sendTF;
	
	@property (nonatomic, assign) int serverSockfd;
	@property (nonatomic, assign) int clientSockfd;
	
	@property (nonatomic, assign) int udpSockfd;
	
	@property (nonatomic, assign) ServerType serType;
	
	- (void)viewDidLoad {
	    [super viewDidLoad];
	    
	    NSString *ip_addr = [self getIPAddress];
	    _locIPTF.text = ip_addr;
	}
	
	#pragma mark - 创建 TCP 监听
	
	- (IBAction)createdTCPServer:(id)sender {
	    
	    _desIPTF.enabled = NO;
	    _desPortTF.enabled = NO;
	    _locPortTF.enabled = NO;
	    
	    [NSThread detachNewThreadSelector:@selector(createdTCPSer) toTarget:self withObject:nil];
	}
	
	- (void)createdTCPSer {
	    
	    self.serType = ServerTypeTCP;
	    
	    BOOL success;
	    int err;
	    
	    // 创建 socket
	    self.serverSockfd = socket(AF_INET, SOCK_STREAM, 0);
	    success = (self.serverSockfd != -1);
	    
	    NSString *logStr = nil;
	    
	    if (success == NO) {
	        
	        logStr = @"创建 socket 失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"创建 socket 成功...
";
	        [self showMessage:logStr];
	        
	        // 本地地址
	        struct sockaddr_in loc_addr;
	        memset(&loc_addr, 0, sizeof(loc_addr));
	        loc_addr.sin_family      = AF_INET;
	        loc_addr.sin_port        = htons(_locPortTF.text.intValue);
	        loc_addr.sin_addr.s_addr = inet_addr(_locIPTF.text.UTF8String);
	        
	        // 绑定
	        err = bind(self.serverSockfd, (const struct sockaddr *)&loc_addr, sizeof(loc_addr));
	        success = (err == 0);
	    }
	    
	    if (success == NO) {
	        
	        logStr = @"socket 绑定失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"socket 绑定成功...
";
	        [self showMessage:logStr];
	        
	        // 监听
	        err = listen(self.serverSockfd, 5);     // 5：最大连接个数
	        success = (err == 0);
	    }
	    
	    if (success == NO) {
	        
	        logStr = @"socket 监听失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"socket 监听成功...
";
	        [self showMessage:logStr];
	        
	        while (true) {      // 循环
	            
	            // 连接的客户端的地址
	            struct sockaddr_in cli_addr;
	            socklen_t cli_addr_Len = sizeof(cli_addr);
	            
	            // 接受客户端的请求，并建立连接
	            self.clientSockfd = accept(self.serverSockfd, (struct sockaddr *)&cli_addr, &cli_addr_Len);
	            success = (self.clientSockfd != -1);
	            
	            if (success) {
	                
	                char *ip_addr = inet_ntoa(cli_addr.sin_addr);
	                int ip_port   = ntohs(cli_addr.sin_port);
	                dispatch_async(dispatch_get_main_queue(), ^{
	                    _desIPTF.text = [NSString stringWithFormat:@"%s", ip_addr];
	                    _desPortTF.text = [NSString stringWithFormat:@"%d", ip_port];
	                });
	                
	                logStr = [NSString stringWithFormat:@"已连接：%s，port：%d
", ip_addr, ip_port];
	                [self showMessage:logStr];
	                
	                char buf[1024];
	                do {
	                    // 返回读取的字节数
	                    ssize_t recvLen = recv(self.clientSockfd, buf, sizeof(buf), 0);
	                    
	                    if (recvLen > 0) {
	                        logStr = [NSString stringWithFormat:@"recv：%@
", [NSString stringWithUTF8String:buf]];
	                        [self showMessage:logStr];
	                    }
	                    
	                } while (strcmp(buf, "exit") != 0);
	            }
	        }
	    }
	}
	
	#pragma mark - 创建 UDP 连接
	
	- (IBAction)connectUDP:(id)sender {
	    
	    [NSThread detachNewThreadSelector:@selector(connectUDP) toTarget:self withObject:nil];
	}
	
	- (void)connectUDP {
	    
	    self.serType = ServerTypeUDP;
	    
	    BOOL success;
	    int err;
	    
	    // 创建 Socket
	    self.udpSockfd = socket(AF_INET, SOCK_DGRAM, 0);
	    success = (self.udpSockfd != -1);
	    
	    NSString *logStr = nil;
	    
	    if (success == NO) {
	        
	        logStr = @"创建 socket 失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"创建 socket 成功...
";
	        [self showMessage:logStr];
	        
	        // 本地地址
	        struct sockaddr_in loc_addr;
	        bzero(&loc_addr, sizeof(loc_addr));
	        loc_addr.sin_port        = htons(_locPortTF.text.intValue);
	        loc_addr.sin_addr.s_addr = inet_addr(_locIPTF.text.UTF8String);
	        
	        // 绑定
	        err = bind(self.udpSockfd, (const struct sockaddr *)&loc_addr, sizeof(loc_addr));
	        success = (err == 0);
	    }
	    
	    if (success == NO) {
	        
	        logStr = @"socket 绑定失败...
";
	        [self showMessage:logStr];
	        
	        return;
	        
	    } else {
	        
	        logStr = @"socket 绑定成功...
";
	        [self showMessage:logStr];
	        
	        // 目标地址
	        struct sockaddr_in des_addr;
	        bzero(&des_addr, sizeof(des_addr));
	        des_addr.sin_family      = AF_INET;
	        des_addr.sin_port        = htons(_desPortTF.text.intValue);
	        des_addr.sin_addr.s_addr = inet_addr(_desIPTF.text.UTF8String);
	        
	        char buf[256];
	        bzero(buf, sizeof(buf));
	        
	        while(1) {
	            
	            // 接收数据
	            socklen_t des_addr_len = sizeof(des_addr);
	            ssize_t recvLen = recvfrom(self.udpSockfd, buf, sizeof(buf), 0, (struct sockaddr*)&des_addr, &des_addr_len);
	            
	            if (recvLen > 0) {
	                logStr = [NSString stringWithFormat:@"recv：%@
", [NSString stringWithUTF8String:buf]];
	                [self showMessage:logStr];
	            }
	        }
	    }
	}
	
	#pragma mark - 发送数据
	
	- (IBAction)btnClick:(id)sender {
	    
	    if (_sendTF.text.length == 0) {
	        return;
	    } else {
	        
	        ssize_t sendLen;
	        
	        if (self.serType == ServerTypeTCP) {
	            
	            // 发送数据
	            sendLen = send(self.clientSockfd, _sendTF.text.UTF8String, strlen(_sendTF.text.UTF8String), 0);
	 
	        } else if (self.serType == ServerTypeUDP) {
	            
	            // 目标地址
	            struct sockaddr_in des_addr;
	            bzero(&des_addr, sizeof(des_addr));
	            des_addr.sin_family      = AF_INET;
	            des_addr.sin_port        = htons(_desPortTF.text.intValue);
	            des_addr.sin_addr.s_addr = inet_addr(_desIPTF.text.UTF8String);
	            
	            // 发送数据
	            sendLen = sendto(self.udpSockfd, _sendTF.text.UTF8String, strlen(_sendTF.text.UTF8String), 0, 
	                             (struct sockaddr *)&des_addr, sizeof(des_addr));
	        }
	        
	        if (sendLen > 0) {
	            NSString *logStr = [NSString stringWithFormat:@"send：%@
", _sendTF.text];
	            [self showMessage:logStr];
	        }
	    }
	}
	
	#pragma mark - 获取本地 IP 地址
	
	- (NSString *)getIPAddress {
	    
	    NSString *address = @"error";
	    struct ifaddrs *interfaces = NULL;
	    struct ifaddrs *temp_addr = NULL;
	    int success = 0;
	    
	    // retrieve the current interfaces - returns 0 on success
	    success = getifaddrs(&interfaces);
	    
	    if (success == 0) {
	        
	        // Loop through linked list of interfaces
	        temp_addr = interfaces;
	        
	        while (temp_addr != NULL) {
	            
	            if (temp_addr->ifa_addr->sa_family == AF_INET) {
	                
	                // Check if interface is en0 which is the wifi connection on the iPhone
	                if ([[NSString stringWithUTF8String:temp_addr->ifa_name] isEqualToString:@"en0"]) {
	                    
	                    // Get NSString from C String
	                    address = [NSString stringWithUTF8String:inet_ntoa(((struct sockaddr_in *)temp_addr->ifa_addr)->sin_addr)];
	                }
	            }
	            temp_addr = temp_addr->ifa_next;
	        }
	    }
	    
	    // Free memory
	    freeifaddrs(interfaces);
	    return address;
	}
	
	// 显示信息
	- (void)showMessage:(NSString *)msg {
	    
	    dispatch_async(dispatch_get_main_queue(), ^{
	        
	        _recvTextView.text = [_recvTextView.text stringByAppendingString:msg];
	    });
	}

Socket7 Socket10