Question

在第一种方法中，我创建了基于sampleProject的客户端 - 服务器应用程序，它将一些数据发送到服务器。

Legend:
sender
    address = reciver ip
    port = reciver port
reciver
    address = null since he is listening
    port = in my case 55555

工作代码

仅出于公共原因而故意跳过错误检查

发件人

-(id*)initForSender:(NSString*)address port:(int)port
 {
   self = [super init];
   if (self) {
        _port = port;
        _address = address;
        tag = 0;
        _udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

        [_udpSocket bindToPort:0 error:&error];
        [_udpSocket beginReceiving:&error];

      return self;
    }
}

-(void)send:(NSData*)data{
     [_udpSocket sendData:data toHost:_address port:_port withTimeout:-1 tag:tag];
     tag++;
}

接收者/听众

-(id*)initForReceiver:(NSString*)address port:(int)port
{
   self = [super init];
   if (self) {
        _port = port;
        _udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
        NSError *error = nil;

       [_udpSocket bindToPort:0 error:&error];
       [_udpSocket beginReceiving:&error];
    }
    return self;
}

- (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
      fromAddress:(NSData *)address
withFilterContext:(id)filterContext
{
    //Do something with receive data
}

组播

但后来我想要发送给许多接收器的客户端。表格我知道sendre或者监听器应该使用[GCDAsyncUdpSocket joinMulticastGroup：error] ;.我运行了堆栈溢出，叔叔谷歌和CococaAsyncSocket（哪里没有字abou udp），匹配收集的信息，并想出了这段代码。我完全相信，这不起作用，但我不知道为什么。

Legend:
sender
    address = sender ip
    port = sender port in my case 55555
reciver
    address = sender ip
    port = sender port in my case 55555

不工作代码

-(id*)initForSender:(NSString*)address port:(int)port
{
    self = [super init];
    if (self) {
        _port = port;
        _address = address;
        _udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
        NSError *error = nil;

        [_udpSocket bindToPort:_port error:&error];
        [_udpSocket joinMulticastGroup:_address error:&error];
        [_udpSocket enableBroadcast:YES error:&error];

    }
    return self;
}

-(void)send:(NSData*)data{
     [_udpSocket sendData:data toHost:_address port:_port withTimeout:-1 tag:tag];
     tag++;
}

接收者/听众

-(id*)initForReceiver:(NSString*)address port:(int)port
{
    self = [super init];
    if (self) {
        _port = port;
        _address = address;
        _udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
         NSError *error = nil;

        [_udpSocket bindToPort:_port error:&error];
        [_udpSocket joinMulticastGroup:_address error:&error];
        [_udpSocket beginReceiving:&error])

    }
    return self;
}

- (void)udpSocket:(GCDAsyncUdpSocket *)sock didReceiveData:(NSData *)data
      fromAddress:(NSData *)address
withFilterContext:(id)filterContext
{
   //Do something with receive data
}

UPDATE：

事实证明，当我使用一些不使用的IP作为address，例如@“224.0.1.1”时，它就会震动，但它感觉很奇怪。我做得对吗？

Answer 1

Multicast addresses是用于多播目的的特殊保留地址。当主机将数据发送到多播地址（组）时，已加入该组的所有主机都将接收数据。
任何希望从多播组接收数据的主机都需要加入该组。 GCDAsyncUdpSocket的三个步骤是:(请注意，组播地址和组端口组合对于所选的多播组必须是唯一的）
```
[_udpSocket bindToPort:_port error:&error];
[_udpSocket joinMulticastGroup:_address error:&error];
[_udpSocket beginReceiving:&error])
```

对于发件人，您不需要这两行。

[_udpSocket bindToPort:0 error:&error];  //bindToPort:0 is same as auto-select sender port by default.
[_udpSocket beginReceiving:&error];   //if you don't want to received, no need for this.

将239.0.0.0-239.255.255.255用于您的专用本地网络。避免224 ...您可以从上面的链接中阅读更多内容。

GCDAsyncUdpSocket和组播发送和接收

工作代码

组播

不工作代码

UPDATE：

1 个答案: