前提

一般流程图：

image.png

一、简单客户端实现（苹果自带的框架）

• 1、与服务器进行连接

- (IBAction)connectToServer {
    //ios里实现sokcet的连接，使用C语言
    
    // 1.绑定地址和端口，与服务器通过三次握手建立连接
    NSString *host = @"127.0.0.1"; // 服务器ip
    int port = 12345; // 连接端口，用来区分 软件/进程
    
    // 2.定义输入输出流
    CFReadStreamRef readStream;  // 输入流，读数据
    CFWriteStreamRef writeStream; // 输出流，写数据
    
    // 3.分配输入输出流的内存空间
    CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)host, port, &readStream, &writeStream);
    
    // 4.把C语言的输入输出流转成OC对象，方便面向对象编程
    _inputStream = (__bridge NSInputStream *)readStream;
    _outputSteam = (__bridge NSOutputStream *)(writeStream);
    
    // 5.设置代理,监听数据接收的状态
    _outputSteam.delegate = self;
    _inputStream.delegate = self;
    
    // 把输入输入流添加到主运行循环(RunLoop)，通过运行循环不断检查端口的数据状态
    // 若加到子线程中，delegate回调也是在子线程中执行
    [_outputSteam scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    [_inputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
    
    // 6.打开输入输出流
    [_inputStream open];
    [_outputSteam open];
}

• 2、输入/输出流代理回调

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode {
//    NSStreamEventNone
//    NSStreamEventOpenCompleted = 1UL << 0,
//    NSStreamEventHasBytesAvailable = 1UL << 1,
//    NSStreamEventHasSpaceAvailable = 1UL << 2,
//    NSStreamEventErrorOccurred = 1UL << 3,
//    NSStreamEventEndEncountered = 1UL << 4
    
    switch (eventCode) {
        case NSStreamEventOpenCompleted:
            NSLog(@"%@",aStream);
            NSLog(@"成功连接建立，形成输入输出流的传输通道");
            break;
            
        case NSStreamEventHasBytesAvailable:
            NSLog(@"有数据可读");
            [self readData];
            break;
            
        case NSStreamEventHasSpaceAvailable:
            NSLog(@"可以发送数据");
            break;
            
         case NSStreamEventErrorOccurred:
            NSLog(@"有错误发生，连接失败");
            break;
            
         case NSStreamEventEndEncountered:
            NSLog(@"正常的断开连接");
            break;
        default:
            break;
    }
}

• 3、读数据

- (void)readData {
    
    //定义缓冲区 这个缓冲区只能存储1024字节
    uint8_t buf[1024];
    
    // 读取数据
    // len为服务器读取到的实际字节数，实际数据可能不满1024字节
    NSInteger len = [_inputStream read:buf maxLength:sizeof(buf)];
    
    // 把缓冲区里的实现字节数转成字符串
    NSString *receiverStr = [[NSString alloc] initWithBytes:buf length:len encoding:NSUTF8StringEncoding];
    NSLog(@"%@",receiverStr);
}

• 4、发数据

- (void)sendData:(NSData *)data {
    [_outputSteam write:data.bytes maxLength:data.length];
}

一、简单服务端实现（GCDAsyncSocket）

• 1、创建socket

- (instancetype)init {
    if (self = [super init]) {
         // 回调线程
        _globalQ = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        //1.创建服务端的socket
        _serverSocket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:_globalQ];
    }
    return self;
}

• 2、监听端口

-(void)startChatServer{
    //2.打开监听端口
    NSError *err;
    [_serverSocket acceptOnPort:54321 error:&err];
    if (!err) {
        NSLog(@"服务开启成功");
    }else{
        NSLog(@"服务开启失败");
    }
}

• 3、与客户端建立连接

- (void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket {
    NSLog(@"服务端的socket %p 客户端的socket %p",sock,newSocket);
    //保存与客户端之间的socket套接字，以后和客户端交换信息需要用到这个newSocket
    [self.clientSocket addObject:newSocket];
    
    //sock 服务端的socket 服务端的socket只负责客户端的连接，不负责数据的读取
    //先读取数据
    [newSocket readDataWithTimeout:-1 tag:100];
}

• 4、服务器写数据给客户端回调

- (void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag {
    NSLog(@"%s",__func__);
}

• 5、服务器收到客户端数据的回调

- (void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag {
    // sock为与客户端连接的套接字

    //接收到数据
    NSString *receiverStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"length:%ld",receiverStr.length);

    // 以下数据处理的流程可以忽略
    // 把回车和换行字符去掉
    receiverStr = [receiverStr stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    receiverStr = [receiverStr stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    
    //判断是登录指令还是发送聊天数据的指令
    //登录指令
    if([receiverStr hasPrefix:@"iam:"]){//登录指令
        // 返回 xxx has joined
        // 获取用户名
        NSString *user = [receiverStr componentsSeparatedByString:@":"][1];
        
        // 响应给客户端的数据
        NSString *respStr = [user stringByAppendingString:@"has joined"];
        //sock
        [sock writeData:[respStr dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];
    }
    
    //聊天指令
    if ([receiverStr hasPrefix:@"msg:"]) {
        //截取聊天消息
        NSString *msg = [receiverStr componentsSeparatedByString:@":"][1];
        [sock writeData:[msg dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];
    }
    
    //quit指令
    if ([receiverStr isEqualToString:@"quit"]) {
        //断开连接
        [sock disconnect];
        //移除socket
        [self.clientSocket removeObject:sock];
        return;
    }

    // 维持输入流的监听
    [sock readDataWithTimeout:-1 tag:100];
}