Open Radar

 
Summary:
See rdar://15857629
In the SKScore API it is possible only to send the total points to show in the leaderboard, but it can be useful to add a new API that is used only to add a delta value to the score already submitted.

Steps to Reproduce:
1. Create an SKScore object
2. Add a value to report

Expected Results:
The value inserted can be specified to be a delta value to sum to the score already present in the leaderboard or create a new one if is the first score sent.

Actual Results:
To add a delta value to the score in the leaderboard first the developer would call the SKLeaderboard API to load the score submitted by the player and then add the value to the one retrieved or send a new one if the methods return an empty array of scores.