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----");
}