Multipeer Connectivity Disconnect

Question

I'm having trouble with staying connected using the Multipeer Connectivity Framework in iOs7. Currently my app is programmatically handling the browsing and advertising using MCNearbyServiceAdvertiser and MCNearbyServiceBrowser. I have an alert view that asks the user if he is a browser or an advertiser. On the return from that view I instantiate either an MCNearbyServiceAdvertiser or Browser accordingly.

#pragma - Alert Delegate
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    if (buttonIndex == 0)
    {
        _browser = [[MCNearbyServiceBrowser alloc]initWithPeer:_peerID serviceType:@"Context-xl"];
        [_browser setDelegate:self];
        [self.detailViewController setRemote:YES];
        [_browser startBrowsingForPeers];
    } else
    {
        _advertiser = [[MCNearbyServiceAdvertiser alloc]initWithPeer:_peerID discoveryInfo:nil serviceType:@"Context-xl"];
        [_advertiser setDelegate:self];
        [self.detailViewController setRemote:NO];
        [_advertiser startAdvertisingPeer];
    }
    [self.detailViewController configureView];
}

My session delegate method peer:...DidChangeState... is getting called twice, once for the connect and again for the disconnect. I'm not stopping the advertiser or browser at all after the session is started. Should I stop browsing/advertising?

I've continued working on it. I thought that maybe setting breakpoints was causing the devices to disconnect, which actually seems to be the case. However, the devices aren't staying connected when running normally. — Corey Zambonie, Oct 01 '13 at 23:03
I'm having the same problem. The devices connect for a bit then disconnect and won't stay connected or reconnect. — James Andrews, Oct 18 '13 at 22:41
It happened a lot when I was doing a file transfer using MCSession's sendData:ToPeer method. I've since switched to opening a stream using the startStream:withName method and the devices have been staying connected. — Corey Zambonie, Oct 21 '13 at 02:02
possible duplicate of [Why does my MCSession peer disconnect randomly?](http://stackoverflow.com/questions/18935288/why-does-my-mcsession-peer-disconnect-randomly) — Diogenes Creosote, Oct 31 '13 at 00:01
I am also getting random disconnects, even when not backgrounded or on breakpoints. Anyone found any solutions? — jjxtra, Nov 30 '13 at 03:35

jjxtra · Answer 1 · 2013-12-16T20:29:36.293

EDIT Used a support ticket with Apple and they confirmed that calling sendData with too much data or too often can cause disconnects.

EDIT My hypothesis is that Apple has a thread or queue that is polling to check if peers are connected. If this thread / queue stalls (i.e. a breakpoint is hit or the app pegs the CPU or does something that takes a while on the main thread) it appears that this causes a disconnect.

Creating my session without encryption seems to have helped performance and with the disconnects, although they still happen.

MCPeerID* peerId = [[MCPeerID alloc] initWithDisplayName:self.displayName];
self.peer = [[MultiPeerPeer alloc] initWithDisplayName:peerId.displayName andPeer:peerId];
self.session = [[MCSession alloc] initWithPeer:peerId securityIdentity:nil encryptionPreference:MCEncryptionNone];

In addition, I have found calling sendData too often (more than 30-60 times a second) can cause the framework to get in a bad state and cause freezes and disconnects.

I actually talked to the Apple engineer's who worked on multi-peer connectivity, and they confirmed that calling sendData too often can result in problems. Maybe iOS 8 will fix this, we'll see... — jjxtra, May 28 '14 at 16:18
Hey, goof to know. Do you have a link to the support ticket? — Omer, Jan 04 '16 at 17:36

Multipeer Connectivity Disconnect

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