Question

Firstly,

I am fairly new to objective c / xcode dev so there is a good chance i am being a muppet. I have written a few simple apps to try things and my most recent one has been testing the gamecentre classes / functionality.

i have linked ok to leaderboards and achievements – but i can’t get challenges working.

I have added the following code…. which is in my .m

         GKLeaderboard *query = [[GKLeaderboard alloc] init];
          query.category = LoadLeaderboard;
          query.playerScope = GKLeaderboardPlayerScopeFriendsOnly;
          query.range = NSMakeRange(1,100);

          [query loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error)
           {NSPredicate *filter = [NSPredicate predicateWithFormat:@"value < %qi", scoreint];
                NSArray *lesserScores = [scores filteredArrayUsingPredicate:filter];

               [self presentChallengeWithPreselectedScores: lesserScores];

           }
           ];

this code is basically taken from apple, just replacing the variable names….
this however gives an error on
[self presentChallengeWithPreselectedScores: lesserScores];

error Implicit conversion of an Objective-C pointer to ‘int64_t *’ (aka ‘long long *’) is disallowed with ARC

LoadLeaderboard is defined as a string
scoreint is defined as integer, thought this may be issue as not int64_t but that does not seem to make a difference.

I am sure for someone who has any kind of a clue this is a straightforward fix. But i am struggling at the moment. So if anyone can be kind and help a fool in need it would be most appreciated

Thanks,
Matt

Answer 1

welcome to Stack Overflow. I don’t know your implementation of presentChallengeWithPreselectedScores method so I can’t tell (although it looks like the method is taking a 64 bit integer and you’re trying to feed it an array).

There are two ways to issue challenges:

1 – This is the easier way – if you’ve successfully implemented leader boards and score posting to game center, the challenges work out of the box in iOS6, the user can always view the leader board – select a submitted score (or a completed achievement) and select “Challenge Friend”.

2 – The second way is to build a friend picker and let the user issue challenges within your game. But considering you’re new to objective-c and game center, it’s not so easy. But for your reference here is how you do it:

when you submit a GKScore object for the leaderboards – you can retain and use that GKScore object (call it myScoreObject) like this:

[myScoreObject issueChallengeToPlayers:selectedFriends message:yourMessage];

where selectedFriends is an NSArray (the friend picker should generate this) – the message is optional and can be used only if you want to send a message to challenged friends.