Encountering runtime error " attempt to insert nil object "

Question

I am trying to write a simple multiplayers Swift program using Xcode 7 beta 5. I encountered the following error at runtime:

[__NSPlaceholderArray initWithObjects:count:]: attempt to insert nil object from objects[0]'
*** First throw call stack

And then I tried and error and found that this piece of code somehow introduced this error:

func setupMatchHandler() {
    /* This function handles invite as sent by other users */

    GKMatchmaker.sharedMatchmaker().matchForInvite(GKInvite().self , completionHandler: { (invitedMatch , invitationError) -> Void in

        if invitationError != nil {
            // error out
            print("Game Center error: \(invitationError)")
        }

        if invitedMatch != nil {
            // success
            print("invitation received!")
        }
    })

}

I wonder can any expert here shed light on what went wrong here? Thanks a million!

sam

Answer 1

Maybe a check for (GKInvite().self != nil) could help?

It seems that it's the only thing that you are inserting via matchForInvite is this one