Simple highscore using preferences (Lua - Corona SDK)

Question

And thanks in advance for your help!

I'm trying to implement in my game an highscore feature using "preferences" in Lua, but i'm missing something, here's my code:

local highscore_letta = system.getPreference( "app", "highscore", "number" )

-- if preference do not exist, create it and set it to 0 (first time playing the game)
if (highscore_letta == nil) then
    local appPreferences =
    {
        highscore = "0"
    }
    system.setPreferences( "app", appPreferences )
end

-- if the score is higher than current highscore, update it with the new one
if (_G.player_score > highscore_letta) then
    local appPreferences =
    {
        highscore = _G.player_score
    }
    system.setPreferences( "app", appPreferences )
end

After the player lose for the first time, the game crashes saying that it's comparing a null value in "highscore_letta". After a second try, the game do not crashes, but it sticks with 0 and never update it at all.

Any advice? I can't figure out what i'm missing. Thanks again!

Answer 1

Try

local highscore_letta = system.getPreference( "app", "highscore", "number" ) or 0

-- if the score is higher than current highscore, update it with the new one
if (_G.player_score > highscore_letta) then
    local appPreferences =
    {
        highscore = _G.player_score
    }
    system.setPreferences( "app", appPreferences )
end