gamecenter.LEADERBOARD_TIME_SCOPE_TODAY,
gamecenter.LEADERBOARD_TIME_SCOPE_WEEK,
gamecenter.LEADERBOARD_TIME_SCOPE_ALLTIME

gamecenter.GK_ERROR_UNKOWN,
gamecenter.GK_ERROR_CACELLED,
gamecenter.GK_ERROR_COMMUNICATIONS_FAILURE,
gamecenter.GK_ERROR_USER_DENIED,
gamecenter.GK_ERROR_INVALID_CREDENTIALS,
gamecenter.GK_ERROR_NOT_AUTHENTICATED,
gamecenter.GK_ERROR_AUTHENTICATION_IN_PROGRESS,
gamecenter.GK_ERROR_INVALID_PLAYER,
gamecenter.GK_ERROR_SCORE_NOT_SET,
gamecenter.GK_ERROR_PARENTAL_CONTROLS_BLOCKED,
gamecenter.GK_ERROR_PLAYER_STATUS_EXEEDS_MAXIMUM_LENGTH,
gamecenter.GK_ERROR_PLAYER_STATUS_INVALID,
gamecenter.GK_ERROR_MATCH_REQUEST_INVALID,
gamecenter.GK_ERROR_UNDERAGE,
gamecenter.GK_ERROR_GAME_UNRECOGNIZED,
gamecenter.GK_ERROR_NOT_SUPPORTED,
gamecenter.GK_ERROR_INVALID_PARAMETER,
gamecenter.GK_ERROR_UNEXPECTED_CONNECTION,
gamecenter.GK_ERROR_CHALLENGE_INVALID,
gamecenter.GK_ERROR_TURN_BASED_MATCH_DATA_TOO_LARGE,
gamecenter.GK_ERROR_TURN_BASED_TOO_MANY_SESSIONS,
gamecenter.GK_ERROR_TURN_BASED_INVALID_PARTICIPANT,
gamecenter.GK_ERROR_TURN_BASED_INVALID_TURN,
gamecenter.GK_ERROR_TURN_BASED_INVALID_STATE,
gamecenter.GK_ERROR_INVITATIONS_DISABLED,
gamecenter.GK_ERROR_PLAYER_PHOTO_FAILURE,
gamecenter.GK_ERROR_UBIQUITY_CONTAINER_UNAVAILABLE,
gamecenter.GK_ERROR_MATCH_NOT_CONNECTED,
gamecenter.GK_ERROR_GAME_SESSION_REQUEST_INVALID

local function login_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)	
	else
		if data.playerID then
		print("Game center initialized with:", data.alias, data.playerID)
        ...
		end
	end
end

gamecenter.login(login_cb)

local function report_score_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	end
end

gamecenter.reportScore({leaderboardId="com.siligame.example.defoldgamecenter.leaderboard", score=message.score}, report_score_cb)

-- OR
gamecenter.reportScore("com.siligame.example.defoldgamecenter.leaderboard", message.score, report_score_cb)

gamecenter.showLeaderboards()

gamecenter.showLeaderboards({timeScope=gamecenter.LEADERBOARD_TIME_SCOPE_WEEK})
-- OR
gamecenter.showLeaderboards(gamecenter.LEADERBOARD_TIME_SCOPE_WEEK)      

gamecenter.showLeaderboards({leaderboardId="com.siligame.example.defoldgamecenter.leaderboard", timeScope=gamecenter.LEADERBOARD_TIME_SCOPE_WEEK})
-- OR
gamecenter.showLeaderboards("com.siligame.example.defoldgamecenter.leaderboard", gamecenter.LEADERBOARD_TIME_SCOPE_WEEK)       

gamecenter.showAchievements()     

local function submit_achievement_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	end
end

gamecenter.submitAchievement({identifier="com.siligame.example.defoldgamecenter.achievementA", percentComplete=45.0}, submit_achievement_cb)  
-- OR
gamecenter.submitAchievement("com.siligame.example.defoldgamecenter.achievementA", percentComplete=45.0, submit_achievement_cb)         

local function reset_achievements_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)	
	end
end

gamecenter.resetAchievements(reset_achievements_cb) 

-- Login --

-- Login callback
local function login_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	else
		if data.playerID then
		print("Game center initialized with:", data.alias, data.playerID)
        ...
		end
	end
end

-- Login
function init(self) 
    if  gamecenter~= nil then
        gamecenter.login(login_cb)
    else
        print("could not connect native code")
    end
end

-- Others --

-- submit achievement callback
local function submit_achievement_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	end
end

-- reset achievement callback
local function reset_achievements_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	end
end

-- report score callback
local function report_score_cb(self, data)
	if(data.error) then
		print("===>code :" .. data.error.code)
		print("===>message :" .. data.error.message)
	end
end

-- Report score to a specified Leaderboard
if message_id == hash("report_scores") then
  if gamecenter~= nil then
     gamecenter.reportScore({leaderboardId="com.siligame.example.defoldgamecenter.leaderboard", score=message.score}, report_score_cb)
  end
-- Show all Leaderboards
elseif message_id == hash("show_leaderboards") then
   if gamecenter~= nil then
      gamecenter.showLeaderboards(gamecenter.LEADERBOARD_TIME_SCOPE_WEEK)
   end  
-- Show a Leaderboard
elseif message_id == hash("show_highscore") then
   if gamecenter~= nil then
      gamecenter.showLeaderboards("com.siligame.example.defoldgamecenter.leaderboard", gamecenter.LEADERBOARD_TIME_SCOPE_WEEK)      
   end     
-- Show Achievements
elseif message_id == hash("show_achievements") then
   if gamecenter~= nil then
     gamecenter.showAchievements()
   end 
-- Submit Achievement
elseif message_id == hash("submit_achievement") then
        gamecenter.submitAchievement({identifier="com.siligame.example.defoldgamecenter.achievementA", percentComplete=45.0}, submit_achievement_cb)  
-- Reset Achievements
elseif message_id == hash("reset_achievements") then
        gamecenter.resetAchievements(reset_achievements_cb)                
end