Could not bind socket to multicast port

[zbrox]

While developing and constantly running/stopping the project, sometimes there would be a bind error and thus SSDP discovery can't be started. This happens seemingly randomly. The branch used is swift-2.1.

The exact error is SSDP discovery did fail with error: Error Domain=UPnAtom Code=0 "Could not bind socket to multicast port" UserInfo={NSLocalizedDescription=Could not bind socket to multicast port}

I checked and GCDAsyncUdpSocket should set SO_REUSEADDR. Also on that development device there is no other app that is started or installed even that uses port 1900. On app termination I call stopSSDPDiscovery. I'm not exactly sure what else can be the problem or how to recover from this without restarting the app manually.

[yidiojoe]

It's only been a couple years, but in case someone is having trouble with this (like I was) here is what fixed the issue for me...

In SSDPExplorer.swift set enableReusePort to true for the GCDAsyncUdpSocket objects before the bind call, such as:

        try unicastSocket?.enableReusePort(true)
        try unicastSocket?.bind(toPort: 0, interface: interface)

... try multicastSocket?.enableReusePort(true) try multicastSocket?.bind(toPort: SSDPExplorer._multicastUDPPort)