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");
}

開啟服務

//啟動sever
- (void)startChatServer{
    NSError *error;
    //開啟一個可接受的ip(本機ip 注意：模擬器獲取不到Ip) 和 端口
    [_serverSocket acceptOnInterface:@"192.168.50.128" port:2333 error:&error];
    if (error) {
        NSLog(@"服務器開啟失敗 error is %@",error);
    }else{
        NSLog(@"服務器開啟成功");
//最重要的來了，開啟后臺模式，要不然退到后臺，再回來就不管用了
    [_serverSocket enableBackgroundingOnSocket];

    }
}

接收客戶端鏈接

#pragma mark 有客戶端建立連接的時候調用
-(void)socket:(GCDAsyncSocket *)sock didAcceptNewSocket:(GCDAsyncSocket *)newSocket{
    NSLog(@"new clientSocket Ip is %@",newSocket.connectedHost);
    
    [_clientSocket addObject:newSocket];
    //newSocket為客戶端的Socket。這里讀取數據
    [newSocket readDataWithTimeout:-1 tag:100];
}

給客戶端回消息
[sock writeData:[@"message ..." dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];

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

收到客戶端發來的消息

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

0x02 客戶端 (Client)

client 端使用原生sdk編寫

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

@end

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

連接到server

- (void)connectServer{
    NSString *host = @"192.168.50.128";
    int port = 2333;
    //創建輸入輸出流
    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;
    
    // 輸入輸出流必須加入主運行runLoop中
    [_inputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    [_outputStream scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
    
    [_inputStream open];
    [_outputStream open];
    
}

給服務端發送消息

- (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(@"客戶端發送消息:%@",msg);
 
}

NSStreamDelegate

#pragma MARK - NSStreamDelegate
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode{
    switch(eventCode) {
            
        case NSStreamEventOpenCompleted:
            NSLog(@"客戶端輸入輸出流打開完成");
            break;
            
        case NSStreamEventHasBytesAvailable:
            NSLog(@"客戶端有字節可讀");
            //讀取服務端發來的消息
            [self readData];
            break;
            
        case NSStreamEventHasSpaceAvailable:
            NSLog(@"客戶端可以發送字節");
            break;
            
        case NSStreamEventErrorOccurred:
            NSLog(@"客戶端連接出現錯誤");
            break;
            
        case NSStreamEventEndEncountered:
            NSLog(@"客戶端連接結束");
            //關閉輸入輸出流
            [_inputStream close];
            [_outputStream close];
            
            //從主運行循環移除
            [_inputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
            [_outputStream removeFromRunLoop:[NSRunLoop mainRunLoop] forMode:NSRunLoopCommonModes];
            break;
        default:
            break;
            
    }
    
}

讀取服務端返回的消息

-(void)readData{
    
    //建立一個緩沖區 可以放1024個字節
    uint8_t buf[1024];
    //返回實際裝的字節數
    NSInteger len = [_inputStream read:buf maxLength:sizeof(buf)];
    //把字節數組轉化成字符串
    NSData *data =[NSData dataWithBytes:buf length:len];
    //從服務器接收到的數據
    NSString *recStr =[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"Socket:讀取從服務端發來的消息:%@",recStr);
}