reset a single gamecenter achievement - ios

Question

In my app I have an achievement for 10 wins in a row. So when the user wins 5 games in a row I report the achievement 50% completed - this works fine. When the user loses some games I call my resetAchievment method which sets the percentage to 0 and reports the percentage again. However when I restart the app the percentage gets read from the GKAchivement and it still shows 50%.
- ( void ) resetAchievement
{
_gamekitAchievement.percentComplete=0.0f;
_counter = 0;
[self report];
}
- ( void ) report
{
_gamekitAchievement.showsCompletionBanner = YES;
[_gamekitAchievement reportAchievementWithCompletionHandler:^(NSError *error)
{
if (error)
{
NSLog(#"reporting Achievment: %# failed, error: %#", _gamekitAchievement.identifier, [error localizedDescription]);
}
}];
}
Is it not possible to report a smaller percentage again - or am I doing something wrong?

Answer 1

I have no actual experience from GameKit at all but from reading the documentation and searching the web it seems you're only able to report progress and not regression(?) Not to mention the fact that you can only reset ALL achievements... Perhaps the following would still help you achieve (ahem) what you want:
Update all your local achievement data with + (void)loadAchievementsWithCompletionHandler:
Store this data in the userDefaults for safety
Do NOT reset the local achievement data
Reset all the achievements with + (void)resetAchievementsWithCompletionHandler:
Change the percentComplete to 0 on the achievement in question.
report progress of all the achievements from your local storage
Now, as I mention, having no hands-on experience with this framework the above might not be practical for a number of reasons I am unaware of (the way progress is presented to the player for instance). Guess it was worth a shot to share the idea anyways...

Answer 2

Short answer: It is not possible to report a smaller percentage again.
Long answer: A lower GameCenter score will not overwrite a higher one.
For example you have a high score of 10 points and it's recorded in GameCenter.
If in the next try you get 5 points and they are submitted to GC, your high score of 10 won't be affected.
Similarly if you try to 'reset' your score, it counts as submitting a new score of 0, so it won't make a difference.
This only applies to scores and achievements submitted to GameCenter, inside your app you can do anything you want (for example your own custom leaderboard or something)

Answer 3

If you think about it, 5 wins is not 50% of the way there, since they could lose the 6th, then win 10 in a row, in which case they played 16 total games and 5 wins was more like 30% of the way there. In this case, it is all or nothing, so don't report anything until they have all 10.

Answer 4

Please be aware that storing the progress towards an achievement in NSUserDefaults doesn't take different GameCenter users into account. That means, if Player A (logged into GameCenter) makes some progress and at 90 % progress another Player B on the same device logs into GameCenter with his own account, he starts with the progress made by Player A.
You might solve this by storing a whole NSDictionary with the Player IDs as keys into NSUserDefaults.

Answer 5

What you'll want to do is save it NSUserdefaults. then, Call the NSUser default and check what number it is by using an IF statement.
-(void)checkAcheivement{
scoreNumber = [NSUserDefaults standardUserDefaults] objectForKey:#"GamesWon"]
if(scoreNumber == 10){
//Run code to save achievement in Game Center(_gamekit stuff)
}
//-(void)checkScoreFire{
//scoreNumber = [NSUserDefaults standardUserDefaults] objectForKey:#"GamesWon"]
//if(scoreNumber == 5){
//Run code to set up alert view for 5 wins below
//UIAlertView* message = [[UIAlertView alloc]
// initWithTitle: #"Alert"
// message: #"You are halfway to the Achievement!"
// delegate: self
// cancelButtonTitle: #"Dismiss"
// [message show];
//}
//to save score use this method:
-(void)saveScore{
scoreNumber = [NSUserDefaults standardUserDefaults] objectForKey:#"GamesWon"]
if(gameScore > scoreNumber){
[[NSUserDefaults standardUserDefaults]setInteger:scoreNumber forKey:#"GamesWon"];
}
This will only post the achievement if it is ten, i suggest not putting the achievement in until then, because it makes it more difficult. I also suggest setting up an AlertView to let the person know they are halfway there. You can do so with the code commented above with the checkScoreFive method. Remember to declare everything in the .h file as well.
IBOutlet UIAlertView *AlertView;
-(void)checkAcheivement;
-(void)checkScoreFire;
-(void)saveScore;
int gameScore;
int scoreNumber;