How to deal with lag spike from gamecenter - swift

Question

My game uses Game Center for scoreboards. At the start of the app I ask Game Center to login.
The problem is that after a variable amount of time Game Center pops up with its "welcome back...." thing and this creates a HUGE latency spike in my app that is already low on resources.
I have played with the completion handlers trying to find out some sort of callback when the banner is done... but nothing!
How am I supposed to handle this? I have a loading screen, could I perhaps not finish loading until the thing has popped up?
Here is my code I use right now
func authenticateLocalPlayer()
{
Holder.loggedIn = false
print("Start Authenticate")
let localPlayer = GKLocalPlayer.localPlayer()
localPlayer.authenticateHandler = {(viewController, error) -> Void in
if (viewController != nil)
{
self.presentViewController(viewController!, animated: false, completion: {self.authenticated()})
}
}
}

Answer 1

I've seen the same thing, and even seen differences in login times on different devices sitting next to each other on the same network. My strategy, which I believe originally came from Apple's docs or WWDC videos but I don't have a reference handy, is to initiate authentication immediately on startup, like so at in my first view controller's viewDidAppear:
Disable the start game button so users can't attempt a session when they can't even log in.
Start authentication
Do all other initiation stuff, animations, etc.
In the authentication handler, if successful, enable the start game button
This way, I move the lag pain to the app startup, which can be somewhat masked by the normal app launch delays, startup animations and what not. When I actually launch a gaming session, I've ensured that login overhead (or failure) is out of the way.
Btw, not directly related to your question, but I noticed that in your authentication handler, you present the view controller if it's present, and assume the user is authenticated if the view controller is nil. Note that when an error occurs, the error value is set but the view controller is nil. So, a nil VC can mean the user is authenticated, but it can also mean that the authentication failed. Always check the value of error first.
localPlayer.authenticateHandler = {(viewController, error) -> Void in
if (error)
{
//check and process the error.
//bail out because we are NOT authenticated
return;
}
if (viewController != nil)
{
self.presentViewController(viewController!, animated: false, completion: {self.authenticated()})
}
}