先UDP组播 socket 再TCP建立长连接

相关概念：
    单播、多播（组播）和广播的区别  http://blog.csdn.net/wangerge/article/details/3931491
    多播（组播）地址范围--224.0.0.0到239.255.255.255
    广播地址： 255.255.255.255

应用场景：
     家庭局域网设备组件一个局域网，各设备提供udp socket监听服务，手机客户端进入此局域网，并向局域网内发送组播或广播，对应设备响应组播并按需要与手机端建立tcp长连接通信

1.服务端：
  - (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    GCDAsyncUdpSocket *serverSocket = [[[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()] autorelease];
    NSError *bindError = nil;
    //bindToPort绑定端口函数，只能使用在充当server 的socket上 client socket不能使用
    //[serverSocket bindToPort:8099 interface:@"en1" error:&bindError]; //en1 随机分配的ip地址
    [serverSocket bindToPort:8099 error:&bindError]; //该socket默认绑定到该机子网卡的ip地址
    if (bindError) {
        NSLog(@"bindError = %@",bindError);
    }
   
    NSError *receiveError = nil;
    [serverSocket beginReceiving:&receiveError]; //开始接收数据，一定要否则后面无法接收数据 不接收数据时调用pauseReceiving
    if (receiveError) {
        NSLog(@"receiveError = %@",receiveError);
    }
    //[serverSocket joinMulticastGroup:@"224.0.1.23" error:nil];//该socket加入到组播224.0.1.23中，之后只要客户端socket向这个组播地址发消息，该socket都能收到 与客户端的发送地址必须一致才能接收
    NSLog(@"%@",[serverSocket localHost]);

   ///////////////////////////服务开启时同时开启TCP服务监听，以便后面建立TCP连接
    GCDAsyncSocket *socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
    NSError *err = nil;
    if(![socket acceptOnPort:8099 error:&err])//tcp socket的监听端口必须要与udp socket的端口一样 后面客户端才能正确与服务端建立tcp连接，因为客户端到时获取的端口是udp socket的端口
    {
        NSLog(@"err.description = %@",err.description);
    }else
    {
        NSLog(@"%@",[NSString stringWithFormat:@"开始监听%d端口.",8099]);
    }
/////////////////////////////
}

udpsocket的关键回调方法：接收到客户端socket发送的消息响应如下
- (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
      fromAddress:(NSData *)address
withFilterContext:(id)filterContext {
   NSLog(@"sock = %@, ReceiveData = %@, fromAddress = %@",sock,[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding],[[NSString alloc] initWithData:address encoding:NSUTF8StringEncoding]);
    NSString *responseMessage = @"已即受到";
    NSString *host = nil;
    uint16_t port = 0;
    [GCDAsyncUdpSocket getHost:&host port:&port fromAddress:address];//可获取客户端socket的ip和端口，不过直接打印address是空的
   
    NSLog(@"Adress = %@ %i",host,port);
    [sock sendData:[responseMessage dataUsingEncoding:NSUTF8StringEncoding] toAddress:address withTimeout:-1 tag:10];//服务端回应客户端
   
}

Tcp socket关键回调方法
- (void)socket:(GCDAsyncSocket *)sender didAcceptNewSocket:(GCDAsyncSocket *)newSocket
{
    NSLog(@"%@",[NSString stringWithFormat:@"建立与%@的连接",newSocket.connectedHost]);
    s = newSocket;
    s.delegate = self;
    [s readDataWithTimeout:-1 tag:0];//必须调用
}

-(void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSString *receive = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"%@",[NSString stringWithFormat:@"%@:%@",sock.connectedHost,receive]);
   
    NSString *reply = [NSString stringWithFormat:@"收到:%@",receive];
   
    [s writeData:[reply dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];
    [s readDataWithTimeout:-1 tag:0];
}

2.客户端：
   - (IBAction)broadCast:(id)sender {
    GCDAsyncUdpSocket *udpSocket = [[[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()] autorelease];
   
    NSError *error = nil;
    [udpSocket enableBroadcast:YES error:&error];//允许广播 必须 否则后面无法发送组播和广播
    NSString *message = @"ttt";
    //[udpSocket sendData:[message dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:10];//该函数只能用户已经连接的socket
    [udpSocket sendData:[message dataUsingEncoding:NSUTF8StringEncoding] toHost:@"224.0.1.23"   port:8099 withTimeout:-1 tag:10];//客户端socket发送组播或是广播 根据host的ip地址来订
    [udpSocket beginReceiving:nil];//必须要  开始准备接收数据
}

UDP 回调函数
  - (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
      fromAddress:(NSData *)address
withFilterContext:(id)filterContext {
    NSLog(@"ReceiveData = %@, fromAddress = %@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding],[[NSString alloc] initWithData:address encoding:NSUTF8StringEncoding]);
    NSString *host = nil;
    uint16_t port = 0;
    [GCDAsyncUdpSocket getHost:&host port:&port fromAddress:address];//从此可以获取服务端回应的ip和端口 用于后面的tcp连接
   
    NSLog(@"Adress = %@ %i",host,port);
   
    //开启tcp连接
    sockeTCP = [[GCDAsyncSocket alloc]initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
    //socket.delegate = self;
    NSError *err = nil;
    if(![sockeTCP connectToHost:host onPort:port error:&err])
    {
       
    }else
    {
        NSLog(@"tcp ok");
        [sockeTCP writeData:[@"发送tcp消息" dataUsingEncoding:NSUTF8StringEncoding] withTimeout:-1 tag:0];
        [sockeTCP readDataWithTimeout:-1 tag:0];
    }
}

TCP 回调函数：
   -(void)socket:(GCDAsyncSocket *)sock didConnectToHost:(NSString *)host port:(uint16_t)port
{
    NSLog(@"%@",[NSString stringWithFormat:@"tcp连接到:%@",host]);
    [sockeTCP readDataWithTimeout:-1 tag:0];
   
}

-(void)socket:(GCDAsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSString *newMessage = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    NSLog(@"tcp newMessage = %@",newMessage);
}