Connecting to an invalid host does not fail

[jan-ekholm]

I use GCDAsyncSocket to connect to an own TCP server of mine. I noticed that the socket never fails nor gives any error when the hostname is invalid and does not exist:

self.socket = [[GCDAsyncSocket alloc] initWithDelegate:self delegateQueue:dispatch_get_main_queue()];

host = @"totallyinvalid";

NSError * error = nil;
if ( ! [self.socket connectToHost:host onPort:29927 withTimeout:10 error:&error] ) {
    NSLog( @"failed to connect" );
    return;
}
if ( error ) {
    NSLog( @"failed to connect: %@", [error localizedDescription] );
    return;
}

Nor are the timeout callbacks called, even when running for a long time. Any way to work around this? The hostnames I've tried with do not resolve to anything at all and even when trying with an invalid IP there is no error.

[krestenkrab]

You need to listen for the socketDidDisconnect:withError: delegate callback. The initial connectToHost:onPort: call just does some basic validation and initiates the connect, later you'll get the error callback mentioned before or socket:didConnectToHost:port: callback.