Hi all,
I am using the AsyncUdpSocket class from the AsyncSocket library
(http://code.google.com/p/cocoaasyncsocket/) to receive UDP packets.
I'm early in development, and all I'm doing is receiving a UDP packet over a
given port, and logging it to the console. However, for some reason my UDP
packet (transmitted from other software) appears to be arriving twice! I'm
able to verify (via an independent UDP monitoring utility) that the software is
only broadcasting each packet once....so something must be wrong with my code.
Can someone help? This is my first Cocoa project. The code's not
pretty...just doing a concept test right now.
The other software is broadcasting UDP packets that look like this:
"X=1.1243533512, Y=18.129583212, Z=194.129182412" (ASCII encoding) and each
line is terminated by a newline character.
Here are the relevant bits of my code, from my view controller:
- (void)viewDidLoad {
[super viewDidLoad];
AsyncUdpSocket *aSyncSocket=[[AsyncUdpSocket alloc] initWithDelegate:self];
//We are the delegate for the asynchronous socket object.
[aSyncSocket bindToPort:1234 error:nil]; //We want to listen on port
1234...don't care about errors for now.
[aSyncSocket receiveWithTimeout:-1 tag:1]; //Start listening for a UDP
packet.
}
#pragma mark AsyncUdpSocket Delegate Method
//This method is called by the AsyncUdpSocket object when a packet is received:
- (BOOL)onUdpSocket:(AsyncUdpSocket *)sock didReceiveData:(NSData *)data
withTag:(long)tag fromHost:(NSString *)host port:(UInt16)port
{
NSString *theLine=[[NSString alloc] initWithData:data
encoding:NSASCIIStringEncoding]; //Convert the UDP data to an NSString
NSLog(@"%@", theLine);
[theLine release];
[aSyncSocket receiveWithTimeout:-1 tag:1]; //Listen for the next UDP
packet to arrive...which will call this method again in turn.
return YES; //Signal that we didn't ignore the packet.
}
Even though the transmitting software sends out a single packet, like this:
"X=1.12345678, Y=2.3456789, Z=3.4567890" (verified independently),
my console keeps showing this:
"X=1.12345678, Y=2.3456789, Z=3.4567890"
"X=1.12345678, Y=2.3456789, Z=3.4567890"
It's as if the packet is not cleared from the AsyncUdpSocket object's queue
until *after* I return YES from the delegate method. If I remove the
[aSyncSocket receiveWithTimeout:-1 tag:1]; line from the delegate method, then
I receive one packet...but of course, since I'm not continuing to put more
"listen" requests into the socket's queue, no more packets are received.
Can anyone who's used AsyncUdpSocket before help out a beginner? Frustrated...
Thanks,
Todd_______________________________________________
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