GCDAsyncsocket broadcast to all IPs

Question

I am trying to implement an IP discoverer app for microchip platform. I am using GCDAsyncSocket to do this. IF I send a specific message, all devices of interest will respond with their network credentials.

With GCDAsyncSocket, If I use a specific IP, I can get a response. But I am not sure how to broadcast this message to all IPs in the network.

My Code: udpSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

- (void)setupSocket
{   
    NSError *error = nil;


    if (![udpSocket bindToPort:0 error:&error])
    {
        [self logError:FORMAT(@"Error binding: %@", error)];
        return;
    }
    if (![udpSocket beginReceiving:&error])
    {
        [self logError:FORMAT(@"Error receiving: %@", error)];
        return;
    }
    [udpSocket enableBroadcast:YES error:&error];
    if (error != nil)
    {
        NSLog(@"Error enableing broadcast: %@", [error description]);
        return;
    }

    [self logInfo:@"Ready"];
}

- (IBAction)send:(id)sender
{
    NSString *host = addrField.text;
    NSError *error = nil;


    NSData *data = [msg dataUsingEncoding:NSUTF8StringEncoding];
    [udpSocket sendData:data toHost:host port:port withTimeout:-1 tag:tag];


    [self logMessage:FORMAT(@"SENT (%i): %@", (int)tag, msg)];

    tag++;
}

Now, how can I make it to send to all IPs instead of only one IP? In the original PC java app, I can see something like

socket = new DatagramSocket(30303);
            socket.setBroadcast(true);
            InetAddress address = InetAddress.getByName("255.255.255.255");
            packet = new DatagramPacket(str.getBytes(),
                    str.length(), address, 30303);

            socket.send(packet);

And I want to do the same on this app. Appreciate some help.

Answer 1

I have used the same socket library in my ios app for the same purpose (searching device on network) the code i have used was..

_broadcastSocket = [[GCDAsyncUdpSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];
if ([_broadcastSocket enableBroadcast:YES error:&error] == false) {
        NSLog(@"Failed to enable broadcast, Reason : %@",[error userInfo]);
    }
[_broadcastSocket sendData:data toHost:@"255.255.255.255" port:5944 withTimeout:-1 tag:5];

Calling sendata function of socket with NSData object will broadcast data to all the ip on the network listening on the given port.