IOS4 – 使用UDP套接字发送数据

我刚刚开始在iPhone上开发网络。 我需要开发一个简单的应用程序来与Wifi路由器交谈。 问题是，wifi盒通过UDP进行通信。 我已经挖了很多，但到目前为止我看过的所有示例代码都有TCP通信的例子，除了一个; UDPEcho示例。

所以，我的问题是：1。我如何知道WiFi网络上的设备是否可以通过WiFi连接？ 2.为了在UDP上进行通信，我可以简单地创建一个套接字，并使用CFSocketSendData方法将数据发送到某个地址吗？

它看起来像UDPEcho示例，首先创建一个主机，然后解析它，然后获取一个地址，并在绑定到套接字后发送一些数据。 我想要一个简单的原始实现，只需发送数据包并接收数据包作为响应。

任何链接或参考都会有所帮助。 更有帮助的是，原始实现的一些基本步骤。 简单来说，我可以执行以下操作：1。使用CFSocketCreate创建套接字，在数据可供读取时指定回调。 2.使用CFSocketSend在套接字上发送数据，指定我要发送的地址。

编辑：我创建了一个类SocketTest，然后调用connect：后跟sendData。 这是代码：

#include "SocketTest.h" @implementation SocketTest - (BOOL)connectSocket{ CFSocketRef appSocket; const CFSocketContext socketContext = { 0, self, NULL, NULL, NULL }; CFRunLoopSourceRef socketRunLoopSourceRef; struct sockaddr_in deviceAddress; /** We have to bind a machine address to the socket which we will create. For this, we need to store our address and port number into a structure of the type, struct_sockaddr_in (since, we will be using IPv4). */ /** Part 1: Create address structure. */ //Clear memory reserved for socket address. memset(&deviceAddress, 0, sizeof(deviceAddress)); //Create our remote device address deviceAddress.sin_addr.s_addr = inet_addr("192.168.0.1"); //Convert string to suitable usage format and store as address. deviceAddress.sin_family = AF_INET; deviceAddress.sin_port = (u_short)9009; //Put the device address into a CFDataRef object. CFDataRef address = CFDataCreate(NULL, (UInt8 *)&deviceAddress, sizeof(struct sockaddr_in)); //If there was a problem with previous call, return with error. if (NULL == address) { return 1; } /** Part 2: Create socket with a signature and add it to run loop. */ //Create a socket signature that specifies the communication protocol and the connection address. const CFSocketSignature signature = { PF_INET, //Protocol family IPv4 SOCK_DGRAM, //Datagram socket IPPROTO_UDP, //Protocol is UDP address //CFDataRef object holding the contents of our remote address. }; //Create socket with the signature just created appSocket = CFSocketCreateConnectedToSocketSignature( NULL, //Default memory allocator &signature, //Signature we created above kCFSocketDataCallBack, //Callback that will read data into a CFData object dataReadyToRead, //The method that will be called as callback &socketContext, 0.0 ); //Create socket /* appSocket = CFSocketCreate( NULL, //Default memory allocator PF_INET, //Protocol Family IPv4 SOCK_DGRAM, //Datagram socket (UDP) IPPROTO_UDP, //Protocol is UDP kCFSocketDataCallBack, //Flag to tell socket to call our callback when data is ready dataReadyCallBack, //The call back function that will be called &socketContext //The socket context ); */ //Create run loop source, with our socket as the source socketRunLoopSourceRef = CFSocketCreateRunLoopSource( NULL, //Default memory allocator appSocket, //Socket created 0 //Highest priority source ); //Add to surrent run loop CFRunLoopAddSource( CFRunLoopGetCurrent(), //Add to current run loop socketRunLoopSourceRef, //Add this run loop source kCFRunLoopDefaultMode //The default mode of the run loop ); CFRelease(socketRunLoopSourceRef); //Return success return 0; } static void receiveData(CFSocketRef socket, CFSocketCallBackType type, CFDataRef address, const void *data, void *info) { //CFSocketSendData(socket, address, (CFDataRef)data, 0.0); CFDataRef buffer; UInt8 *receivedData; buffer = (CFDataRef)data; CFDataGetBytes( buffer, CFRangeMake(0,CFDataGetLength(theData)), &receivedData ); //Show data received in label. } BOOL sendData: (void *)data{ CFSocketError socketErrors; static char helloworld[] = "\r\nHello world"; CFDataRef _packet = CFDataCreate(NULL, (const UInt8 *)helloworld, strlen(helloworld)); socketErrors = CFSocketSendData(appSocket, NULL, packet, 0.0); return; } @end 

但是，我仍然无法将数据发送到我的服务器。 我在另一台机器上运行一个简单的C编码监听服务器来测试我的代码。

此外，尝试了AsyncUDPSocket库并取得了很大成功。 但是，想知道事情的复杂性。 AsyncUDPSocket库获取并解析IPv4或IPv6地址。 在我的SocketTest代码中，我只是指定了一个IPv4地址。

所以，我提出的问题是，为什么这段代码不起作用？ 是否有一些非常小的东西，但是我错过了非常重要的东西？ 将不胜感激任何帮助。

谢谢。