Never finished [GKAchievement loadAchievementsWithCompletionHandler:] - iphone

Question

I use the function [GKAchievement loadAchievementsWithCompletionHandler:] to restore the current player achievements in initialization. But the completionHander was never called.
- (void)loadAchievements
{
[GKAchievement loadAchievementsWithCompletionHandler:^(NSArray *achievements, NSError *error)
{
if (error == nil) // !!-- if a breakpoint is set here, it would never be reached
{
#synchronized(_achievementsDictionary)
{
for (GKAchievement* achievement in achievements)
[_achievementsDictionary setObject:achievement forKey:achievement.identifier];
NSLog(#"achievements loaded");
}
}
else
{
NSLog(#"Error in loading achievements: %#", error);
}
}];
}
However, a similar function, [GKAchievementDescription loadAchievementDescriptionsWithCompletionHandler:] works well:
- (void) retrieveAchievmentMetadata
{
[GKAchievementDescription loadAchievementDescriptionsWithCompletionHandler:
^(NSArray *descriptions, NSError *error) {
if (error != nil)
{
NSLog(#"Error in loading achievement descriptions: %#", error);
}
if (descriptions != nil)
{
#synchronized(_achievementsMetaDataDictionary)
{
for (GKAchievementDescription* desc in descriptions)
{
_achievementsMetaDataDictionary[desc.identifier] = desc;
}
}
NSLog(#"achievement descriptions loaded");
}
}];
}
What might be the problem?

Answer 1

It comes a bit late, but maybe it helps someone else.
The fact is that GKAchievement loadAchievementsWithCompletionHandler: loads all the achievements which the local player made progress on. This means, if there are fresh achievements set up in the regarding iTunes Connect app (without any progress), they won't be loaded. Some progress has to be reported first!
On the other hand GKAchievementDescription loadAchievementDescriptionsWithCompletionHandler: is meant to get all the information about every of the available achievements for the regarding iTunes Connect app. The description provides the identifier of the achievement, too.
For a fresh achievement the flow is the following:
Load the achievement description. (GKAchievementDescription loadAchievementDescriptionsWithCompletionHandler:)
Report some progress for the achievement to Game Center. The GKAchievement can be created based on data in GKAchievementDescription. (GKAchievementDescription reportAchievements:withCompletionHandler:)
From this point on, load the progress of the achievement to set up your app on start. (GKAchievement loadAchievementsWithCompletionHandler:)

Answer 2

Did you check that the returned descriptions NSArray does not have 0 elements?
if( !descriptions.count )
printf( "User has not submitted _any_ progress on _any_ achievements\n" ) ;
else for (GKAchievementDescription* desc in descriptions) ..
Note the descriptions array here only returns the collection of achievements this user has previously submitted progress on, not the array of all achievements ever registered on GameCenter for this app.