Are all iOS GameCenter callbacks performed in the main thread unless otherwise noted?

Question

I read a lot about GameCenter from various sources ... especially in the Apple documentation, as well as in some Apress books about using the multiplayer GameCenter game, but I cannot find a clear answer on whether I can trust callbacks like matchmakerViewController: didFindMatch or match: didReceiveData: fromPlayer (just to name a couple of examples) to always be in the main thread.

Sometimes they explicitly say in the Apple documentation that the call will always be in the main thread, but they are not consistent with the fact that they are clear for each function.

Apress books tend to be completely paranoid in flow, so they use dispatch_async to make sure they get into the main stream.

My question is simple ... Can I trust that unless Apple says otherwise, the calls will be in the mainstream or I need to be paranoid like Apress books.

(Please do not answer questions such as “just paranoid everywhere and don't worry about it”)

Answer 1

I searched for the same thing, and the most explicit comment from Apple that I can find about this problem is contained in the comments at the head of the GameCenterManager.m file in the GKTapper sample application that they provide ( https://developer.apple.com/ library / ios / samplecode / gktapper / Listings / Classes_GameCenterManager_m.html ):

"GameCenter , . , , . , , ( dealloc'd) ."

( ) .
, GameKit , , , , .

- (void) callDelegate: (SEL) selector withArg: (id) arg error: (NSError*) err
{
    assert([NSThread isMainThread]);
    if([delegate respondsToSelector: selector])
    {
        if(arg != NULL)
        {
            [delegate performSelector: selector withObject: arg withObject: err];
        }
        else
        {
            [delegate performSelector: selector withObject: err];
        }
    }
    else
    {
        NSLog(@"Missed Method");
    }
}    



- (void) callDelegateOnMainThread: (SEL) selector withArg: (id) arg error: (NSError*) err
{
    dispatch_async(dispatch_get_main_queue(), ^(void)
    {
       [self callDelegate: selector withArg: arg error: err];
    });
}

GKTapper , , , GameKit.