demo 地址 https://github.com/Liuchunqi3240/demo/tree/master/iOS_Socket/TCP

0x01 Server端

server端使用CocoaAsyncSocket 完成
pod 'CocoaAsyncSocket'

#import "GCDAsyncSocket.h"
@interface ViewController ()<GCDAsyncSocketDelegate>

@end

@implementation ViewController{
    GCDAsyncSocket *_serverSocket;
    dispatch_queue_t _golbalQueue;
    NSMutableArray *_clientSocket;
}

初始化 server

- (void)initServer{
    if (!_serverSocket) {
        _clientSocket = [NSMutableArray array];
        _golbalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        _serverSocket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:_golbalQueue];
    }
    NSLog(@"server inited");
}

开启服务

//启动sever
- (void)startChatServer{
    NSError *error;
    //开启一个可接受的ip(本机ip 注意：模拟器获取不到Ip) 和 端口
    [_serverSocket acceptOnInterface:@"192.168.50.128" port:2333 error:&error];
    if (error) {
        NSLog(@"服务器开启失败 error is %@",error);
    }else{
        NSLog(@"服务器开启成功");
//最重要的来了，开启后台模式，要不然退到后台，再回来就不管用了
    [_serverSocket enableBackgroundingOnSocket];

    }
}

接收客户端链接

#pragma mark 有客户端建立连接的时候调用
-(void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket{
    NSLog(@"new clientSocket Ip is %@",newSocket.connectedHost);
    
    [_clientSocket addObject:newSocket];
    //newSocket为客户端的Socket。这里读取数据
    [newSocket readDataWithTimeout:-1 tag:100];
}

给客户端回消息
[sock writeData:[@"message ..." dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];

#pragma mark - GCDAsyncSocketDelegate
-(void)socket:(GCDAsyncSocket *)sock didWriteDataWithTag:(long)tag{
    [sock readDataWithTimeout:-1 tag:100];
}

收到客户端发来的消息

#pragma mark - GCDAsyncSocketDelegate
-(void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag{
    
    //接收到数据
    NSString *receiverStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"服务端收到的数据:%@",receiverStr);
    [sock writeData:[@"mes received" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];
}

0x02 客户端 (Client)

client 端使用原生sdk编写

@interface ViewController ()<NSStreamDelegate>
@property (weak, nonatomic) IBOutlet UITextField *mesTextField;

@end

@implementation ViewController{
    NSInputStream *_inputStream;
    NSOutputStream *_outputStream;
}

连接到server

- (void)connectServer{
    NSString *host = @"192.168.50.128";
    int port = 2333;
    //创建输入输出流
    CFReadStreamRef readStreamRef;
    CFWriteStreamRef writeStreamRef;
    CFStreamCreatePairWithSocketToHost(NULL, (__bridge CFStringRef)host, port, &readStreamRef, &writeStreamRef);
    _inputStream = (__bridge NSInputStream *)(readStreamRef);
    _outputStream = (__bridge NSOutputStream *)(writeStreamRef);
    _inputStream.delegate = self;
    _outputStream.delegate = self;
    
    // 输入输出流必须加入主运行runLoop中
    [_inputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    [_outputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    
    [_inputStream open];
    [_outputStream open];
    
}

给服务端发送消息

- (IBAction)sendMes:(id)sender {
    NSString *msg = self.mesTextField.text;
    NSData *msgData = [msg dataUsingEncoding:NSUTF8StringEncoding];
    [_outputStream write:msgData.bytes maxLength:msgData.length];
    self.mesTextField.text = @"";
    NSLog(@"客户端发送消息:%@",msg);
 
}

NSStreamDelegate

#pragma MARK - NSStreamDelegate
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode{
    switch(eventCode) {
            
        case NSStreamEventOpenCompleted:
            NSLog(@"客户端输入输出流打开完成");
            break;
            
        case NSStreamEventHasBytesAvailable:
            NSLog(@"客户端有字节可读");
            //读取服务端发来的消息
            [self readData];
            break;
            
        case NSStreamEventHasSpaceAvailable:
            NSLog(@"客户端可以发送字节");
            break;
            
        case NSStreamEventErrorOccurred:
            NSLog(@"客户端连接出现错误");
            break;
            
        case NSStreamEventEndEncountered:
            NSLog(@"客户端连接结束");
            //关闭输入输出流
            [_inputStream close];
            [_outputStream close];
            
            //从主运行循环移除
            [_inputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
            [_outputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
            break;
        default:
            break;
            
    }
    
}

读取服务端返回的消息

-(void)readData{
    
    //建立一个缓冲区 可以放1024个字节
    uint8_t buf[1024];
    //返回实际装的字节数
    NSInteger len = [_inputStream read:buf maxLength:sizeof(buf)];
    //把字节数组转化成字符串
    NSData *data =[NSData dataWithBytes:buf length:len];
    //从服务器接收到的数据
    NSString *recStr =[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"Socket:读取从服务端发来的消息:%@",recStr);
}