ios - Showing leaderboard crashes app because showViewController isn't supported -

what right way present game center leaderboards in ios 7? code below crashes on showviewcontroller because supports ios 8. other stack overflow posts suggest using presentviewcontroller ios 7, shows blank leaderboard.

func showleaderboards() {     // user logged gamecenter?     if (!gklocalplayer.localplayer().authenticated) {         println("local player not authenticated")         // show message         return     }      // if here, user authenticated. present leaderboards.     var gcviewcontroller = gkgamecenterviewcontroller()     gcviewcontroller.gamecenterdelegate = self     gcviewcontroller.viewstate = gkgamecenterviewcontrollerstate.leaderboards     gcviewcontroller.leaderboardidentifier = highscoresleaderboardkey     self.showviewcontroller(gcviewcontroller, sender: self)     self.navigationcontroller?.pushviewcontroller(gcviewcontroller, animated: true) } 

if app targets ios 7.x, should use following code:

self.presentviewcontroller(gcviewcontroller, animated: true, completion: nil) 

instead of:

self.showviewcontroller(gcviewcontroller, sender: self)