网络：用 socket 做简单聊天

#import "ViewController.h"#import <sys/socket.h> // 没注释#import <netinet/in.h>#import <arpa/inet.h>@interface ViewController ()@property (weak, nonatomic) IBOutlet UITextField *ipAdress;@property (weak, nonatomic) IBOutlet UITextField *port;@property (weak, nonatomic) IBOutlet UITextField *messageInput;@property (weak, nonatomic) IBOutlet UILabel *resultLabel;@property (nonatomic, assign) int clientSocket;@end@implementation ViewController- (IBAction)connection:(id)sender {    [self createSocketAndConnectionWithIPAddress:self.ipAdress.text port:[self.port.text integerValue]];}- (IBAction)send:(id)sender {    self.resultLabel.text = [self sendAndRecv:self.messageInput.text];}- (void)createSocketAndConnectionWithIPAddress:(NSString *)IPAddress port:(NSInteger)port {    // 创建socket    /**     参数解析     第 1个参数 domain 协议域(AF_INET,IPV4 网络开发) (IPV6 不需要管)     第 2个参数 type socket类型,SOCK_STREAM(TCP)/SOCK_DGRAM(UDP)     第三个参数 protocol 协议,如果输 0,可以根据第 2 个参数, 自动选择协议     返回值:如果返回>0 则表 成功 */    int result = socket(AF_INET, SOCK_STREAM, 0);    if (result > 0) {        NSLog(@"创建成功%d",result);    }    // 连接    /**     1. 第一个 socket     2. 服务器地址     */    struct sockaddr_in serverAddress;    // 设置ip 127.0.0.1    serverAddress.sin_addr.s_addr = inet_addr([IPAddress UTF8String]);    // 设置端口号(高低位转换)    serverAddress.sin_port = htons(port);    // 设置协议    serverAddress.sin_family = AF_INET;    // 连接socket    int connectResult = connect(result, (const struct sockaddr *)&serverAddress, sizeof(serverAddress));    if (connectResult == 0) {        self.resultLabel.text = @"连接成功";    }    self.clientSocket = result;}// 发送消息和接收消息- (NSString *)sendAndRecv:(NSString *)sendMsg {    NSString *message = sendMsg;    // 发送消息    /*     1. socket     2. 发送的内容     3. 内容的长度     发送的标记 通常写 0 就可以     */    ssize_t sendResult = send(self.clientSocket, [message UTF8String], strlen([message UTF8String]), 0);    NSLog(@"%ld",sendResult);    // 接收    /*     1, socket     2. 接收的数据     3. 接收的长度     4. 写0代表阻塞式     */    uint8_t buff[1024];    //    NSLog(@"buff -- %ld",sizeof(buff));    ssize_t recvResult = recv(self.clientSocket, buff, sizeof(buff), 0);    //    NSLog(@"%ld",recvResult);    // 把收到的数据转成OC    return [[NSString alloc]initWithBytes:buff length:recvResult encoding:NSUTF8StringEncoding];}- (void)closeConnection {    close(self.clientSocket);}- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.}/* 1. ip 找到对应的电脑 2. 端口号 找到对应的程序 3. 协议 发送内容方式 */- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {}@end