Question

In application, invitationDidFail is being called, some time it connects properly, but sometime it doesn’t…

what can be possible reasons of denying the connection?

// Display an alert sheet indicating a failure to connect to the peer.
- (void) invitationDidFail:(SessionManager *)session fromPeer:(NSString *)participantID
{
NSString *str;
if (alertView.visible) {
    // Peer cancelled invitation before it could be accepted/rejected
    // Close the invitation dialog before opening an error dialog
    [alertView dismissWithClickedButtonIndex:0 animated:NO];
    [alertView release];
    str = [NSString stringWithFormat:@"%@ is busy.\nPlease again", participantID];
    //[peerList removeAllObjects];
    [self peerListDidChange:nil];
    [self.tableData reloadData];
    //[self TwoPlayer:self];
} else {
    // Peer rejected invitation or exited app.
    str = [NSString stringWithFormat:@"%@ is busy.\nPlease try again", participantID];
    //[peerList removeAllObjects];
    [self peerListDidChange:nil];
    [self.tableData reloadData];
    //[self TwoPlayer:self];
  }
}

Even it doesn’t call this method, It is sure that device is not paired to any other device, then what are reasons that sometime it do accept and call didReceivedInvitation method, or some time it does deny by calling invitationDidFail.

// Invitation dialog due to peer attempting to connect.
- (void) didReceiveInvitation:(SessionManager *)session fromPeer:(NSString     *)participantID;
{
[alertView dismissWithClickedButtonIndex:1 animated:NO];

NSString *str = [NSString stringWithFormat:@"Incoming Invite from %@", participantID];
if (alertView.visible) {
    [alertView dismissWithClickedButtonIndex:0 animated:NO];
    [alertView release];
}
alertView = [[UIAlertView alloc] 
             initWithTitle:str
             message:@"Do you wish to accept?" 
             delegate:self 
             cancelButtonTitle:@"Decline" 
             otherButtonTitles:nil];
[alertView addButtonWithTitle:@"Accept"]; 
[alertView show];
}

Answer 1

When I was recently writing an application using connections, I used GKSession. I spent weeks trying to debug connection issues with it and in the end I gave up and stopped using it. There seems to be a number of issues with GKSession when connecting especially if you disconnect and then attempt to reconnect within a short time (a short time could be 1 minute or more). It seems that the connection doesn’t properly get dropped and then it doesn’t recreate the connection properly.

In the end I took out all the GKSession code and used this instead. Worked a treat – no more connection issues.

GCD Async Socket