Multipeer Connectivity Not Connecting Programmatically

Question

I am creating an iOS/macOS app that uses remote control functionality via the Multipeer Connectivity Framework. Since the device to be remotely monitored and controlled will run over an extended period of time, it's not viable to use the automatic view controller methods since the monitoring device may be locked or go to sleep and then disconnect the connection. So I'm using the programatic approach so that when the monitoring devices lose connection, they will automatically pair up when they are unlocked/woken up and the app is started again. My connection works fine using the ViewController method but not the programatic delegate approach. The advertising, browsing and inviting works fine, but when the invitation is accepted on the remote side I get several errors and then a failed connection. What's weird is that several of the errors are GCKSession errors.

So why is it trying to use the GameCenter framework? And why is it failing after accepting the invitation? Could it just be a bug in the Xcode 8 / Swift 3 /iOS 10 / macOS Sierra Beta SDKs?

[ViceroyTrace] [ICE][ERROR] ICEStopConnectivityCheck() found no ICE check with call id (2008493930)
[GCKSession] Wrong connection data. Participant ID from remote connection data = 6FBBAE66, local participant ID = 3A4C626C
[MCSession] GCKSessionEstablishConnection failed (FFFFFFFF801A0020)
Peer Changing
Failed
[GCKSession] Not in connected state, so giving up for participant [77B72F6A] on channel [0]

Here is the code from my connection class

func startAdvertisingWithoutUI () {

    if advertiserService == nil {
        advertiserService = MCNearbyServiceAdvertiser (peer: LMConnectivity.peerID, discoveryInfo: nil, serviceType: "mlm-timers")
        advertiserService?.delegate = self
        session.delegate = self
    }

    advertiserService?.startAdvertisingPeer()

}

func browserForNearbyDevices () {

    if browserService == nil {
        browserService = MCNearbyServiceBrowser (peer: LMConnectivity.peerID, serviceType: "mlm-timers")
        browserService?.delegate = self
        session.delegate = self
    }

    browserService?.startBrowsingForPeers()
}

func sendInvitation(to peer: MCPeerID) {

    browserService?.invitePeer(peer, to: session, withContext: nil, timeout: 60)

}

func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didReceiveInvitationFromPeer peerID: MCPeerID, withContext context: Data?, invitationHandler: (Bool, MCSession?) -> Void) {

    let trustedNames = GetPreferences.trustedRemoteDevices

    for name in trustedNames {

        if name == peerID.displayName {
            invitationHandler(true,session)
            return
        }
    }

    invitationHandler (false, session)
}

Answer 1

The problem for me was that I never set the delegate of MCSession. I got all the same error messages that the OP mentioned, which made me think the connection was broken, but really I just forgot to set the delegate. After setting the delegate, all the error messages still printed, but otherwise my delegate methods got called normally upon receiving a message!

I've inflicted this problem on myself twice. Hopefully this helps someone reading along!

Answer 2

None has worked for me.
I've resolved only disabling encryption...

let session = MCSession(peer:myPeerId, securityIdentity: nil, encryptionPreference: MCEncryptionPreference.none)

Answer 3

When the peerID used to make the session and the peerID used to make the advertiser or browser do not match, I get this part of the error.

[GCKSession] Wrong connection data. Participant ID from remote connection data = 6FBBAE66, local participant ID = 3A4C626C

Once peerIDs match, that part of the error goes away.

There might still be some other connection problems though.