How to implement "NSUserDefaults" functionality equivalent in Corona? - iphone

Question

All I want is to save my user(player) highscores, and this information to persist between application(game) launches in Corona SDK (Lua). I do want it to work on iOS and Android nicely. My highscores data is actually two lua tables containing numbers.
What's the correct and easiest way to do it?

Answer 1

You may save the scores into a table, and then serialize it into json format text file.
local json=require("json")
local savefile="scores.json"
scores=
{
{
level=1,
status=0,
highscore=0,
},
{
level=2,
status=0,
highscore=0,
},
}
function getScore(filename, base)
-- set default base dir if none specified
if not base then
base = system.DocumentsDirectory
end
-- create a file path for corona i/o
local path = system.pathForFile(filename, base)
-- will hold contents of file
local contents
-- io.open opens a file at path. returns nil if no file found
local file = io.open(path, "r")
local scores
if file then
-- read all contents of file into a string
contents = file:read( "*a" )
if content ~= nil then
scores=json.decode(content)
end
io.close(file) -- close the file after using it
end
return scores
end
function saveScore(filename, base)
-- set default base dir if none specified
if not base then
base = system.DocumentsDirectory
end
-- create a file path for corona i/o
local path = system.pathForFile(filename, base)
-- io.open opens a file at path. returns nil if no file found
local file = io.open(path, "wb")
if file then
-- write all contents of file into a string
file:write(json.encode(scores))
io.close(file) -- close the file after using it
end
end
The global scores variable can be manipulated like a normal table, and when you want to load or save the scores table you can call the functions above.