因为业务需要，需要用广播发送一个字段，在iOS开发中，用到了AsynSocket。
1.定义一个属性，负责发送和接受数据
#define YX_Local_Host @"255.255.255.255"
#define YX_Lockl_Port 48899
@property(nonatomic,strong)AsyncUdpSocket *sendSocket;
2.在viewDidload上初始化这个socket
self.sendSocket=[[AsyncUdpSocket alloc]initWithDelegate:self];
//需要有这个初始化，不知道为什么
[self.sendSocket bindToAddress:@"0.0.0.0" port:5666 error:nil];
[self.sendSocket receiveWithTimeout:-1 tag:0];
3.在需要的时候出发它，我这里是在button点击事件出发的
NSString *sendString=@"HF-A11ASSISTHREAD";
NSData *data=[sendString dataUsingEncoding:NSUTF8StringEncoding];
[self.sendSocket sendData:data toHost:YX_Local_Host port:YX_Lockl_Port withTimeout:30 tag:0];
[self.sendSocket enableBroadcast:YES error:nil];
4.发送出去以后，使用AsyncUdpSocket的代理，接受数据，并对需要的数据进行处理。
-(BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port{
NSString *receiveData=[[NSString alloc ]initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"-----receiveData----%@---------",receiveData);
[self.sendSocket receiveWithTimeout:-1 tag:0];
return YES;
}
- (void)onUdpSocket:(AsyncUdpSocket *)sock didNotReceiveDataWithTag:(long)tag dueToError:(NSError *)error{
NSLog(@"没有收到");
}
iOS UDP 广播 AsyncSocket 用法
原文：http://www.cnblogs.com/ljlkfx/p/4973438.html
