iOS oc udp 包发送和接收

UDP是一种无连接的协议，因此在iOS中使用UDP发送和接收数据与TCP有所不同。以下是OC实现UDP发送和接收的基本步骤：

发送UDP包：

1. 创建UDP socket:

int udpSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

2. 设置发送地址和端口：

struct sockaddr_in serverAddr;
memset(&serverAddr, 0, sizeof(serverAddr));
serverAddr.sin_family = AF_INET;
serverAddr.sin_addr.s_addr = inet_addr("目标IP地址");
serverAddr.sin_port = htons(目标端口);

3. 发送数据：

NSString *message = @"hello";
const char *msg = [message UTF8String];
sendto(udpSocket, msg, strlen(msg), 0, (struct sockaddr *)&serverAddr, sizeof(serverAddr));

接收UDP包：

1. 创建UDP socket:

int udpSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);

2. 设置socket端口和地址：

struct sockaddr_in localAddr;
memset(&localAddr, 0, sizeof(localAddr));
localAddr.sin_family = AF_INET;
localAddr.sin_addr.s_addr = htonl(INADDR_ANY);
localAddr.sin_port = htons(本地端口);
bind(udpSocket, (struct sockaddr *)&localAddr, sizeof(localAddr));

3. 接收数据：

char buffer[1024];
struct sockaddr_in clientAddr;
socklen_t clientAddrLen = sizeof(clientAddr);
ssize_t recvLen = recvfrom(udpSocket, buffer, sizeof(buffer), 0, (struct sockaddr *)&clientAddr, &clientAddrLen);
if (recvLen > 0) {
    NSString *message = [[NSString alloc] initWithBytes:buffer length:recvLen encoding:NSUTF8StringEncoding];
}

注意：在使用UDP协议时，需要注意数据包的大小和可靠性问题，因为UDP是无连接的，数据包可能会丢失或乱序。在实际应用中，需要根据具体情况选择合适的协议和方法。