The following very simple example worked for me. Verified with wireshark

if (!udpSocket) {
    udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
    [udpSocket enableBroadcast:YES error:nil];
}

NSData *data = [@"Test Message" dataUsingEncoding:NSUTF8StringEncoding];

[udpSocket sendData:data toHost:@"255.255.255.255" port:12345 withTimeout:-1 tag:tag++];

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Thank you, i will try your code. And how do u receive answer?

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i'm initializing udpSocket from other controller, may be this is the problem, when i put my send data code with initialization code everything works, if i put it somewhere else to other method - no, just doesnt send.

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send data to exact IP works, but doesnt work to broadcast IP

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My code for initialize:

self.udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
self.udpSocket.delegate  = self;

NSError *error = nil;

if (![self.udpSocket bindToPort:port error:&error]) { NSLog(@"Error starting server (bind): %@", error); return; }

if (![ self.udpSocket  beginReceiving:&error])
{ [udpSocket close];
    NSLog(@"Error starting server (recv): %@", error);  return;
}

NSLog(@"Udp Echo server started on port %hu", [udpSocket localPort]);
isRunning = YES;
// --------------------

My code to send broadcast:

NSString mysubnet = [[NSString alloc] initWithFormat: @"%i.%i.%i.255", myip1,myip2,myip3];
NSData datatosend=[UDPString dataUsingEncoding:NSUTF8StringEncoding];

NSLog(@"udpSocket sendData %@ %i",mysubnet, port);
// [udpSocket beginReceiving:nil];
[ self.udpSocket  enableBroadcast:YES error:nil];

//[udpSocket joinMulticastGroup:mysubnet error:nil];
[ self.udpSocket sendData:datatosend toHost:mysubnet port:port withTimeout:-1 tag:0];
[ self.udpSocket enableBroadcast:NO error:nil];

I marked if i try to send data (not broadcasting) it sends but doesn't receive anything.

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Did you implement the didReceiveData delegate function? If so, does the function ever get accessed? If didReceiveData is not accessed, sniff your packets on the network to verify they are indeed being sent.

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i think i found the problem, i created several instances of one class and it made big problems, i also downloaded last version.

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Hi fstanley,

I am having a problem. When I try to use GCDAsyncUdpSocket via the simple code you provided above on April 11, 2012 to broadcast I keep getting a socket close error indicating that the network can't be reached.

Am I missing some setup code not shown?

Note: I am working on a project that needs to work on legacy OS. The iPad has iOS 8.1.3; XCODE 6.2.

On a related side note: My project needs to do a broadcast for part of its function but once a client is identified, the app works fine with normal GCDAsyncUdpSocket functions. I have a BSD sockets solution that generates the proper client response to the broadcast, however, I can't get my app to hear the client replies.

Here is my BSD code that works:

int service_port = 8023;
NSString *          rawMsg = @"ucget serial_number\r";
const char * theAddr;
NSData *            theData;

// Create a socket
int socketfd = socket( AF_INET, SOCK_DGRAM, 0 );

if(localIpAddress == nil) localIpAddress = [self getIPAddress];
theAddr = [localIpAddress UTF8String];

struct sockaddr_in ip4addr;
ip4addr.sin_family = AF_INET;
ip4addr.sin_port = htons(service_port);
ip4addr.sin_addr.s_addr = inet_addr(theAddr);
memset(ip4addr.sin_zero, '\0', sizeof ip4addr.sin_zero);

int ret = bind(socketfd, (struct sockaddr*)&ip4addr, sizeof ip4addr);

// Enable broadcast
int broadcastEnable=1;
ret = setsockopt(socketfd, SOL_SOCKET, SO_BROADCAST, &broadcastEnable, sizeof(broadcastEnable));

//turn non-blocking
ret = fcntl(socketfd, F_SETFL, O_NONBLOCK);

//udp broadcast
struct sockaddr_in address; // Make an endpoint
address.sin_family = AF_INET;
address.sin_port = htons(service_port);
address.sin_addr.s_addr = inet_addr("255.255.255.255");
memset(address.sin_zero, '\0', sizeof address.sin_zero);

theData = [rawMsg dataUsingEncoding:NSUTF8StringEncoding];
assert(theData != nil);
ret = sendto(socketfd, [theData bytes], [theData length], 0, (const struct sockaddr *) &address, sizeof(address));

NSLog(@"sendto: bytes sent = %zd", ret);

ret = close(socketfd);
assert(ret == 0);

What I am looking for is code that will receive the data the client sends back resulting from the above BSD socket broadcast.

Thank you

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Error in send() function. when use multicast in ios version higher than 12.3.

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This issue has been marked as stale, it will be closed automatically if there is no further activity.

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