Getting a player alias

NSMutableArray *playerIDs = [NSMutableArray arrayWithCapacity:match.participants.count];
for (GKTurnBasedParticipant *part in match.participants) {
    if([part.playerID isKindOfClass:[NSString class]]){
        [playerIDs addObject:part.playerID];
    }
}


[GKPlayer loadPlayersForIdentifiers:playerIDs withCompletionHandler:^(NSArray *players, NSError *error) {
    for (GKPlayer *player in players) {

       //get the aliases
}


}];