Corona SDK (LUA) timers and countdowns

Question

I have this game where a function spawns random objects every time a timer fires. It look like this:

function showCountDown (event)
    -- Condition to show and hide countdown
    if countDownNumber == 0 then
        spawnShit = 0
        timer.cancel( timerSpawn )
        timer.cancel(countdownTimer)
        print( 'NO MORE SPAAAAAAAAAAAAAAAWWNS' )
    end

    if countDownNumber >= -1 then
        countDownNumber = countDownNumber -1 
        countDownText.text = countDownNumber
        spawnShit = 1
    end

    if score == nil then
        score = 0
    end

    return true
end

The problem is the timer somehow insists on stopping on -2 instead of on 0, which is quite frustrating. Can anyone see what I'm doing wrong? Maybe you have a better method for creating a countdown timer that triggers different events(stops spawning objects, start win/lose/pause screen etc.

Also it seems like (from looking at the console during testing) that the function showCountDown is triggered about 3 times extra, after the spawnShit = 0, timer.cancel(myTimers) is fired, which is odd because I'm canceling the timer that triggers the event.

Answer 1

You have

if countDownNumber >= -1 then
    countDownNumber = countDownNumber - 1 

This means that the if block will be entered whenever countDownNumber is larger or equal to -1, i.e. any positive number, 0, and -1. Inside the block, it gets decreased by 1 so the last value will be -2.

You probably want >= 1, which will make its last value 0:

if countDownNumber >= 1 then
        countDownNumber = countDownNumber -1