官方网站:http://code.google.com/p/cocoaasyncsocket/

这里只上例子，自己在项目中使用的，绝对能使用，如果有疑问，欢迎留言讨论。

将AsyncUdpSocket.h AsyncUdpSocket.m 导入到你的工程中，

在自己建立的util中，加入一下代码

-(void)sendSearchBroadcast{

NSString* bchost=@"255.255.255.255"; //这里发送广播

[self sendToUDPServer:@"hello udp" address:bchost port:BCPORT];

}

-(void)sendToUDPServer:(NSString*) msg address:(NSString*)address port:(int)port{

AsyncUdpSocket *udpSocket=[[[AsyncUdpSocket alloc]initWithDelegate:self]autorelease]; //得到udp util

NSLog(@"address:%@,port:%d,msg:%@",address,port,msg);

//receiveWithTimeout is necessary or you won't receive anything

[udpSocket receiveWithTimeout:10 tag:2]; //设置超时10秒

[udpSocket enableBroadcast:YES error:nil]; //如果你发送广播，这里必须先enableBroadcast

NSData *data=[msg dataUsingEncoding:NSUTF8StringEncoding];

[udpSocket sendData:data toHost:address port:port withTimeout:10 tag:1]; //发送udp

}//下面是发送的相关回调函数

-(BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port{

NSString* rData= [[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]

autorelease];

NSLog(@"onUdpSocket:didReceiveData:---%@",rData);

return YES;

}

-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotSendDataWithTag:(long)tag dueToError:(NSError *)error{

NSLog(@"didNotSendDataWithTag----");

}

-(void)onUdpSocket:(AsyncUdpSocket *)sock didNotReceiveDataWithTag:(long)tag dueToError:(NSError *)error{

NSLog(@"didNotReceiveDataWithTag----");

}

-(void)onUdpSocket:(AsyncUdpSocket *)sock didSendDataWithTag:(long)tag{

NSLog(@"didSendDataWithTag----");

}

-(void)onUdpSocketDidClose:(AsyncUdpSocket *)sock{

NSLog(@"onUdpSocketDidClose----");

}