I've read that Game Center Leaderboard scores are only updated when the newly posted score is greater than the already existing score.
This made me wonder if it is possible at all to have a Game Center Leaderboard that stores scores counting down, for example "time to complete level". Can this still be achieved with the correct setup of the Leaderboard, for example with sorting and formatting modifiers?
And just to confirm, is it really not possible to have a Game Center Leaderboard simply accept the value that you send to it, regardless of whether it is greater or smaller?
You can choose low to high or high to low leaderbord type in iTunes Connect.
And you can always send any value to Game Center server, it's just that it will not save it unless it's higher* than the current score.
* if it's a low to high leaderboard, the value that is lower is actually counted as a higher score.
来源：https://stackoverflow.com/questions/7780649/is-it-possible-to-have-a-game-center-lowestscore-leaderboard