iOS 使用 socket 实现即时通信示例（非第三方库）

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

@interface ClientModel : NSObject
@property(nonatomic,assign)int clientSocket;
@property(nonatomic,copy)NSString *clientName;
@end

#import "ViewController.h"

#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#import "ClientModel.h"
static int const kMaxConnectCount = 5;

@interface ViewController()
@property (weak) IBOutlet NSTextField *textField;
//@property (nonatomic,assign)int client_socket; //客户端socket
@property (unsafe_unretained) IBOutlet NSTextView *textView;
 @property (nonatomic,strong)NSMutableArray *clientArray;
 @property (nonatomic,strong)NSMutableArray *clientNameArray;
@end

@implementation ViewController

- (NSMutableArray *)clientArray {
 if (!_clientArray) {
  _clientArray = [NSMutableArray array];
 }
 return _clientArray;
}
- (NSMutableArray *)clientNameArray {
 if (!_clientNameArray) {
  _clientNameArray = [NSMutableArray array];
 }
 return _clientNameArray;
}

- (void)viewDidLoad {
 [super viewDidLoad];
 // Do any additional setup after loading the view.
 //创建socket
 int server_socket = socket(AF_INET, SOCK_STREAM, 0);
 if (server_socket == -1) {
  NSLog(@"创建失败");
  [self showLogsWithString:@"socket创建失败"];

 }else{
  //绑定地址和端口
  struct sockaddr_in server_addr;
  server_addr.sin_len = sizeof(struct sockaddr_in);
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(1234);
  server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
  bzero(&(server_addr.sin_zero), 8);

  int bind_result = bind(server_socket, (struct sockaddr*)&server_addr, sizeof(server_addr));
  if (bind_result == -1) {
   NSLog(@"绑定端口失败");
   [self showLogsWithString:@"绑定端口失败"];

  }else{
   if (listen(server_socket, kMaxConnectCount)==-1) {
    NSLog(@"监听失败");
    [self showLogsWithString:@"监听失败"];

   }else{
    for (int i = 0; i < kMaxConnectCount; i++) {
     //接受客户端的链接
     [self acceptClientWithServerSocket:server_socket];
    }
   }
  }
 }
}


- (void)setRepresentedObject:(id)representedObject {
 [super setRepresentedObject:representedObject];

 // Update the view, if already loaded.
}

//创建线程接受客户端
-(void)acceptClientWithServerSocket:(int)server_socket{
 struct sockaddr_in client_address;
 socklen_t address_len;
 dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
 dispatch_async(queue, ^{
  //创建新的socket
  while (1) {
   int client_socket = accept(server_socket, (struct sockaddr*)&client_address,&address_len );
   if (client_socket == -1) {
    [self showLogsWithString:@"接受客户端链接失败"];
    NSLog(@"接受客户端链接失败");
   }else{
    NSString *acceptInfo = [NSString stringWithFormat:@"客户端 in,socket:%d",client_socket];
    [self showLogsWithString:acceptInfo];

    //接受客户端数据
    [self recvFromClinetWithSocket:client_socket];
   }
  }
 });
}

//接受客户端数据
- (void)recvFromClinetWithSocket:(int)client_socket{
 while (1) {
  //接受客户端传来的数据
  char buf[1024] = {0};
  long iReturn = recv(client_socket, buf, 1024, 0);
  if (iReturn>0) {
   NSLog(@"客户端来消息了");
   NSString *str = [NSString stringWithCString:buf encoding:NSUTF8StringEncoding];
   [self showLogsWithString:[NSString stringWithFormat:@"客户端来消息了:%@",str]];
   [self checkRecvStr:str andClientSocket:client_socket];
  }else if (iReturn == -1){
   NSLog(@"读取消息失败");
   [self showLogsWithString:@"读取消息失败"];
   break;
  }else if (iReturn == 0){
   NSLog(@"客户端走了");
   [self showLogsWithString:[NSString stringWithFormat:@"客户端 out socket:%d",client_socket]];
   NSMutableArray *array = [NSMutableArray arrayWithArray:self.clientArray];
   for (ClientModel *model in array) {
    if (model.clientSocket == client_socket) {
     [self.clientNameArray removeObject:model.clientName];
     [self.clientArray removeObject:model];
    }
   }

   close(client_socket);

   break;
  }
 }
}

 //检查接受到的字符串
- (void)checkRecvStr:(NSString*)str andClientSocket:(int)socket{
 if ([str hasPrefix:@"name:"]) {
  NSString *name = [str substringFromIndex:5];

  ClientModel *model = [[ClientModel alloc] init];
  model.clientSocket = socket;
  model.clientName = name;


  if (self.clientArray.count > 0) {
   int flag = 999;
   //用户名不能相同
   int i = 0;

   for (ClientModel *client in self.clientArray) {

    //改名
    if (client.clientSocket == socket) {
     NSString *oldName = self.clientNameArray[i];
     self.clientNameArray[i] = name;
     self.clientArray[i] = model;

     for (ClientModel *oldclient in self.clientArray) {
      [self sendMsg:[NSString stringWithFormat:@"%@ 改名 %@",oldName,name] toClient:oldclient.clientSocket];
      [self showLogsWithString:[NSString stringWithFormat:@"%@ 改名 %@",oldName,name]];
      NSString *list = [self.clientNameArray componentsJoinedByString:@","];
      //向客户端推送当前在线列表
      [self sendMsg:[NSString stringWithFormat:@"list:%@",list] toClient:oldclient.clientSocket];
     }

     flag = 2;

    }else{
     if ([client.clientName isEqualToString:model.clientName]) {
      //用户名已存在
      flag = 1;
      break;
     }
    }
    i++;

   }
   if (flag != 1 & flag != 2) {
    [self.clientArray addObject:model];
    [self.clientNameArray addObject:model.clientName];
    //向客户端推送当前在线列表
    for (ClientModel *client in self.clientArray) {
     [self sendMsg:[NSString stringWithFormat:@"%@,上线了",name] toClient:client.clientSocket];
     NSString *list = [self.clientNameArray componentsJoinedByString:@","];
     //向客户端推送当前在线列表
     [self sendMsg:[NSString stringWithFormat:@"list:%@",list] toClient:client.clientSocket];
    }

    //给当前客户端发送一条欢迎信息
    NSString *msg = [NSString stringWithFormat:@"Welcome %@ !",name];
    [self sendMsg:msg toClient:socket];
    [self showLogsWithString:msg];

   }else if (flag == 1){
    [self sendMsg:@"注册用户名失败，用户名已经存在，请重新设置用户名" toClient:socket];
    [self showLogsWithString:[NSString stringWithFormat:@"socket %d 注册用户名失败，设置的用户名已经存在",socket]];

    for (ClientModel *model in self.clientArray) {

     [name isEqualToString:model.clientName];
    }



   }
  }else{
   [self.clientArray addObject:model];
   [self.clientNameArray addObject:model.clientName];
   //向客户端推送当前在线列表
   //给当前客户端发送一条欢迎信息
   NSString *msg = [NSString stringWithFormat:@"Welcome %@ !",name];
   [self sendMsg:msg toClient:socket];
   [self showLogsWithString:msg];

   NSString *list = [self.clientNameArray componentsJoinedByString:@","];
   //向客户端推送当前在线列表
   [self sendMsg:[NSString stringWithFormat:@"list:%@",list] toClient:socket];

  }

 }
 //给某人发消息
 else if ([str hasPrefix:@"to:"]){
  NSRange nameRange = [str rangeOfString:@"*"];
  NSString *name = [str substringWithRange:NSMakeRange(3, nameRange.location-3)];
  NSString *content = [str substringFromIndex:nameRange.location+1];
  NSString *fromClientName;
  //找出发送者
  for (ClientModel *model in self.clientArray) {
   if (socket == model.clientSocket) {
    fromClientName = model.clientName;
    break;
   }
  }

  //给目标发送信息
  for (ClientModel *model in self.clientArray) {
   if ([name isEqualToString:model.clientName]) {
    NSString *msg = [NSString stringWithFormat:@"%@ to you\n%@",fromClientName,content];
    [self sendMsg:msg toClient:model.clientSocket];

    [self showLogsWithString:[NSString stringWithFormat:@"%@ 发送给 %@ 内容是：%@",fromClientName,name,content]];
    break;

   }
  }

 }
}

//给客户端发送信息
- (void)sendMsg:(NSString*)msg toClient:(int)socket{
 char *buf[1024] = {0};
 const char *p1 = (char*)buf;
 p1 = [msg cStringUsingEncoding:NSUTF8StringEncoding];
 send(socket, p1, 1024, 0);
}

 //在界面上显示日志
- (void)showLogsWithString:(NSString*)str {
 dispatch_async(dispatch_get_main_queue(), ^{
  NSString *newStr = [NSString stringWithFormat:@"\n%@",str];
  self.textView.string = [self.textView.string stringByAppendingString:newStr];
 });
}

@end

#import "ViewController.h"
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
@interface ViewController ()<UITableViewDelegate,UITableViewDataSource>
//服务器socket
@property (nonatomic,assign)int server_socket;

//UI
@property (weak, nonatomic) IBOutlet UITextField *userNameField;
@property (weak, nonatomic) IBOutlet UITextView *chatView;
@property (weak, nonatomic) IBOutlet UITextField *msgField;
@property (weak, nonatomic) IBOutlet UILabel *toName;
@property (weak, nonatomic) IBOutlet UIView *onlineUserView;
@property (nonatomic,strong)UITableView *onlineTable;

//user列表
@property (nonatomic,strong)NSMutableArray *userArray;

@end

@implementation ViewController
- (NSMutableArray *)userArray {
 if (!_userArray) {
  _userArray = [NSMutableArray array];
 }
 return _userArray;
}
- (void)viewDidLoad {
 [super viewDidLoad];
 [self.userNameField becomeFirstResponder];
 self.userNameField.text = @"";
 self.msgField.text = @"";
 //添加table用户列表
 self.onlineTable = [[UITableView alloc] initWithFrame:self.onlineUserView.frame style:UITableViewStylePlain];
 self.onlineTable.delegate = self;
 self.onlineTable.dataSource = self;
 [self.view addSubview:self.onlineTable];

 int server_socket = socket(AF_INET, SOCK_STREAM, 0);
 if (server_socket == -1) {
  NSLog(@"创建失败");
 }else{
  //绑定地址和端口
  struct sockaddr_in server_addr;
  server_addr.sin_len = sizeof(struct sockaddr_in);
  server_addr.sin_family = AF_INET;
  server_addr.sin_port = htons(1234);
  server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");
  bzero(&(server_addr.sin_zero), 8);

  //接受客户端的链接
  dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
  dispatch_async(queue, ^{
   //创建新的socket
   int aResult = connect(server_socket, (struct sockaddr*)&server_addr, sizeof(struct sockaddr_in));
   if (aResult == -1) {
    NSLog(@"链接失败");
   }else{
    self.server_socket = server_socket;
    [self acceptFromServer];
   }
  });
 }
}

//从服务端接受消息
- (void)acceptFromServer{
 while (1) {
  //接受服务器传来的数据
  char buf[1024];
  long iReturn = recv(self.server_socket, buf, 1024, 0);
  if (iReturn>0) {
   NSString *str = [NSString stringWithCString:buf encoding:NSUTF8StringEncoding];

   //筛选前缀
   if ([str hasPrefix:@"list:"]) {
    NSString *arrayStr = [str substringFromIndex:5];
    NSArray *list = [arrayStr componentsSeparatedByString:@","];
    self.userArray = [NSMutableArray arrayWithArray:list];
    dispatch_async(dispatch_get_main_queue(), ^{
     [self.onlineTable reloadData];
    });
    NSLog(@"当前在线用户列表：%@",arrayStr);
   }else{
    //回到主线程 界面上显示内容
    [self showLogsWithString:str];
   }

  }else if (iReturn == -1){
   NSLog(@"接受失败-1");
   break;
  }
 }
}

//在界面上显示日志
- (void)showLogsWithString:(NSString*)str {
 dispatch_async(dispatch_get_main_queue(), ^{
  NSString *newStr = [NSString stringWithFormat:@"\n%@",str];
  self.chatView.text = [self.chatView.text stringByAppendingString:newStr];
 });
}

- (void)didReceiveMemoryWarning {
 [super didReceiveMemoryWarning];
 // Dispose of any resources that can be recreated.
}

//设置用户名
- (IBAction)clickSetUserName:(id)sender {
 NSString *msg = [NSString stringWithFormat:@"name:%@",self.userNameField.text] ;
 [self sendMsg:msg];
// [self showLogsWithString:msg];
 [self.msgField becomeFirstResponder];
}

//发送信息
- (IBAction)clickSendMsg:(id)sender {
 if ([self.msgField.text isEqualToString:@""] || ![self.userArray containsObject:self.userNameField.text] || [self.toName.text isEqualToString:self.userNameField.text]) {
  [self showLogsWithString:@"请设置用户名、检查发送对象、消息不能为空"];
  return;
 }
 NSString *msg = [NSString stringWithFormat:@"to:%@*%@",self.toName.text,self.msgField.text];
 [self sendMsg:msg];
 NSString *displayMsg = [NSString stringWithFormat:@"to:%@\n%@",self.toName.text,self.msgField.text];
 [self showLogsWithString:displayMsg];
 self.msgField.text = @"";

}

//给客户端发送信息
- (void)sendMsg:(NSString*)msg {
 char *buf[1024] = {0};
 const char *p1 = (char*)buf;
 p1 = [msg cStringUsingEncoding:NSUTF8StringEncoding];
 send(self.server_socket, p1, 1024, 0);
}

#pragma mark - TableViewDelegate & dataSource
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
 return self.userArray.count;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
 static NSString *cellId = @"onlinetableviewcellid";
 UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellId];
 if (cell == nil) {
  cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId];
 }else{
  NSLog(@"cell重用了");
 }
 cell.textLabel.text = self.userArray[indexPath.row];
 return cell;
}

//点击cell
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
 self.toName.text = self.userArray[indexPath.row];
 [self.msgField becomeFirstResponder];
}
@end