iPhone Developement : Why does GKLeaderboard loadScoresWithCompletionHandler: return a null value

I'm working With Game Center right now and I have a issue with GC. When I'm using initWithPlayerIDs:, I don't get any score when loadScoresWithCompletionHandler: callback is called.

GKLeaderboard *leaderBoard = [[[GKLeaderboard alloc] initWithPlayerIDs:[NSArray arrayWithObject:gcPlayerID]] autorelease];
leaderBoard.timeScope = GKLeaderboardTimeScopeAllTime;
leaderBoard.category = @"SomeLeaderboard";

[leaderBoard loadScoresWithCompletionHandler:  ^(NSArray *scores, NSError *error) {
 if (error == nil) 
 {
     // scores is null
     // ...
 }

But when I'm doing:

GKLeaderboard *leaderBoard = [[[GKLeaderboard alloc] init] autorelease];
leaderBoard.timeScope = GKLeaderboardTimeScopeAllTime;
leaderBoard.category = @"SomeLeaderboard";

[leaderBoard loadScoresWithCompletionHandler:  ^(NSArray *scores, NSError *error) {
 if (error == nil) 
 {
     for (GKScore* score in scores) 
        if ([score.playerID isEqualToString:gcPlayerID])
        {
            // Got something here
            return;
        }
 }

It's working.

I'm using the 2nd method at the moment but it will make time to process if there is m开发者_如何学编程any score.

Does anyone have the same issue ?

Thanks.

I'm afraid that with the given info I don't have an answer as to why initWithPlayerIDs: is not working. However, I might be able to simplify your filtering for the local player score in the 2nd method. A GKLeaderboard has a property localPlayerScore that is valid only after loadScoresWithCompletionHandler: has completed. localPlayerScore then gives the GKScore for the local player. Your 2nd method would then look like this:

[leaderBoard loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
    if (error == nil) 
    {
        GKScore* myScore = leaderboard.localPlayerScore; 
    }
 }

Hope this helps a little.

Try to narrow the type of scores to those you really want to process. For example request the score for the logged in player and for global time scope etc.

I am using something like the following code snippet in my own game and it is fast:

// Load score for player
     GKLeaderboard *board = [[GKLeaderboard alloc] initWithPlayerIDs:[NSArray arrayWithObject:myGCPlayerID]];

     board.timeScope = GKLeaderboardTimeScopeAllTime;
     board.playerScope = GKLeaderboardPlayerScopeGlobal;
     board.category = @"myGCCategory";

     [board loadScoresWithCompletionHandler:^(NSArray *scores, NSError *error) {
      if(error != nil) {
       NSLog(@"Error loading score:\n%@", [error localizedDescription]);
      }

      if(scores != nil) {
       for(int i=0; i<[scores count]; i++) {
        GKScore *score = (GKScore *)[scores objectAtIndex:i];

        if(([score.playerID isEqualToString:myGCPlayerID]) &&
           (score.value > playerLastScore)) {
         playerLastScore = score.value;
        }
       }
      }
     }];

     [board release];

You may also apply a more optimized score loop as it is in your code. I hope this helps.