游戏中心领导板错误

Question

我为游戏中心排行榜创建了这个代码，我总是得到Thread 1 signal Sigabrt。 NSLOG总是这样说：

2014-04-15 15:27:28.441 GameCenter[38225:60b] -[GKGameCenterViewController setLeaderboardDelegate:]: unrecognized selector sent to instance 0xb48dd90
2014-04-15 15:27:28.442 GameCenter[38225:60b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[GKGameCenterViewController setLeaderboardDelegate:]: unrecognized selector sent to instance 0xb48dd90'
*** First throw call stack:

在我用于实现排行榜的代码的屏幕截图下方：

或者/请在这里查看这个问题：https://stackoverflow.com/questions/23068184/game-center-leaderboard-doesnt-work-in-xcode