Corona SDK（LUA）產生對象和計時器問題

Question

我正在嘗試生成高於屏幕高度的對象以使其下降。 到目前為止，我編寫的代碼可以工作，但是當我讓場景用盡時，請返回並再次啟動級別，場景有2個問題：1.生成函數“ spawnObjects”似乎每0.5秒觸發兩次，但有時，但始終在第二次運行。 在大多數情況下，控制台看起來觸發3（就像它們正在堆疊）2。在第二次運行時，應該在計時器變為0或更少時運行的函數沒有。

這是我的代碼，它可能很笨拙，並且有值，而其他地方則沒有。 這是因為我一直在努力爭取計時器，而現在（仍然有點計時器）已經有幾天了，我嘗試了很多不同的方法。 希望任何人都可以看到我在做錯什么，如果您對countDown計時器和/或產生對象的方式有更好的解決方案，那么我將嘗試任何方式。

local composer = require( "composer" )
local scene = composer.newScene()
local myData = require( "myData" )
local physics = require("physics")
physics.setDrawMode( "hybrid" )
-- forward references
local w = display.actualContentWidth
local h = display.actualContentHeight
local dropCount = 0
local spawnShit = 0
local spawnTime = 17
local countdownTimer
local score = 0
local countNumber = 10
local countDownNumber = 10
local scoreT = display.newText( {text="Score: "..score, font=system.nativeSystemFont, fontSize=14,} )
scoreT.x = w * 0.5
scoreT.y = h * 0.1
local countDownText = display.newText( {text="", font=system.nativeSystemFont, fontSize=14} )
countDownText.x = w * 0.5
countDownText.y = h * 0.2
local drop01 = display.newImage("drop01.png")
drop01.x = -100
local drop02 = display.newImage("drop02.png")
drop02.x = -100
local drop03 = display.newImage("drop03.png")
drop03.x = -100
local drop04 = display.newImage("drop04.png")
drop04.x = -100
local timerSpawn

-- Display objects
local background = display.newImage( "bluebg.png" )
background.x = w*0.5
background.y = h*0.5
background.width = w 
background.height = h 

local bckBtn = display.newText({text="<--BACK", font=system.nativeSystemFont, fontSize=14})
bckBtn.x = 50
bckBtn.y = 20


local egon = display.newImage( "Egon.png" )
egon.x = w*0.5
egon.y = h*0.85
egon.width = 100
egon.height = 97



--functions

function goBack (event)

    if "began" == event.phase then

        elseif event.phase == "ended" then

    composer.gotoScene("select", "fade", 500)

    end




    return true

end

 function moveEgon (event)
    egon.x = event.x
 end

------------------------------------------------vvv---------------------------------------------------
------------------------------------------------vvv---------------------------------------------------
------------------------------------------------vvv---------------------------------------------------
 function spawnObjects (event)

        dropCount = math.random(1,4)



        if stopTimer == 1 then
            timer.cancel(timerSpawn)
            timerSpawn = nil
            spawnShit = nil
        end
        if spawnShit == 1 then
            print( 'spawnShit' )
            if dropCount == 1 then
            -- Drop01 function and settings
            drop01 = display.newImage( "drop01.png" )
            drop01.x = math.random(10, 470)
            drop01.y = 40
            drop01.width = 50
            drop01.height = 50
            drop01.myName = "01"
            physics.addBody( drop01, "dynamic", {density=0.1, friction=0.1, bounce=0.8 } )
            elseif dropCount == 2 then
                --Do shit for drop02
            drop02 = display.newImage( "drop02.png" )
            drop02.x = math.random(10, 470)
            drop02.y = 40
            drop02.width = 50
            drop02.height = 50
            drop02.myName = "02"
                physics.addBody( drop02, "dynamic", {density=0.1, friction=0.1, bounce=0.8 } )
                elseif dropCount == 3 then
            drop03 = display.newImage( "drop03.png" )
            drop03.x = math.random(10, 470)
            drop03.y = 40
            drop03.width = 50
            drop03.height = 50
            drop03.myName = "03"
            physics.addBody( drop03, "dynamic", {density=0.9, friction=0.1, bounce=0.8 } )
                    elseif dropCount == 4 then
            drop04 = display.newImage( "drop04.png" )
            drop04.x = math.random(10, 470)
            drop04.y = 40
            drop04.width = 50
            drop04.height = 50
            drop04.myName = "04"
            physics.addBody( drop04, "dynamic", {density=0.9, friction=0.1, bounce=0.8 } )
            end

        end
        return true
end

---------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------

 function onCollision (event)

    if "began" == event.phase then
        --v--do shit when touching surface

    if event.other.myName == "01" then
        -- Do shit for drop01 -- 
        -- Change score, powersups etc
        event.other:removeSelf( )
    end

        if event.other.myName == "02" then
            -- Do shit for drop02 -- 
        -- Change score, powersups etc
        event.other:removeSelf( )
    end

        if event.other.myName == "03" then 
            -- Do shit for drop03 -- 
        -- Change score, powersups etc
        event.other:removeSelf( )

        end

        if event.other.myName == "04" then
            -- Do shit for drop04 -- 
        -- Change score, powersups etc
        event.other:removeSelf( )
        end

    elseif "ended" == event.phase then 
    -- Do shit when leaving surfaces
end 

    return true

 end
------------------------------------------------vvv---------------------------------------------------
------------------------------------------------vvv---------------------------------------------------
------------------------------------------------vvv---------------------------------------------------
function showCountDown (event)
-- Condition to show and hide countdown
    if countDownNumber <= 0  then
        timer.cancel(event.source)
        countDownTimer = nil
        spawnShit = 0
        print( 'NO MORE SPAAAAAAAAAAAAAAAWWNS' )
    else 
        countDownNumber = countDownNumber -1 
        countDownText.text = countDownNumber
         spawnShit = 1
    end
    return true
end

---------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------

--function scene:create( event )
function scene:create( event )
    local sceneGroup = self.view

    -- Initialize the scene here.
    -- Example: add display objects to "sceneGroup", add touch listeners, etc

    --Listeners

    background:addEventListener( "touch", moveEgon )
    bckBtn:addEventListener( "touch", goBack )
    egon:addEventListener( "collision", onCollision )
    --SceneGroup insert
    sceneGroup:insert( background )
    sceneGroup:insert(egon)
    sceneGroup:insert(bckBtn)
    sceneGroup:insert(drop01)
    sceneGroup:insert(drop02)
    sceneGroup:insert(drop03)
    sceneGroup:insert(drop04)
    sceneGroup:insert(scoreT)
    sceneGroup:insert(countDownText)


    end


-- "scene:show()"
function scene:show( event )

    local sceneGroup = self.view
    local phase = event.phase

    if ( phase == "will" ) then
        -- Called when the scene is still off screen (but is about to come on screen).
    elseif ( phase == "did" ) then
        -- Called when the scene is now on screen.
        -- Insert code here to make the scene come alive.
        -- Example: start timers, begin animation, play audio, etc.
        physics.start( )
        timercount = 10



            -- ADD physic bodies ----
            physics.addBody( egon, "static", {density=0.1, friction=0.1, bounce=0.8 } )
            countDownNumber = 10
            countdownTimer = timer.performWithDelay( 1000, showCountDown, countNumber )
            ----------- Timers ------------
            timerSpawn = timer.performWithDelay(500, spawnObjects, 0 )


    end
end


-- "scene:hide()"
function scene:hide( event )

    local sceneGroup = self.view
    local phase = event.phase

    if ( phase == "will" ) then
        -- Called when the scene is on screen (but is about to go off screen).
        -- Insert code here to "pause" the scene.
        -- Example: stop timers, stop animation, stop audio, 
        --timer.pause( timerSpawn )
        physics.stop()

        spawnShit = 0
        timerSpawn = nil
        countdownTimer = nil
        physics.removeBody( egon )



    elseif ( phase == "did" ) then
        -- Called immediately after scene goes off screen.
    end
end


-- "scene:destroy()"
function scene:destroy( event )

    local sceneGroup = self.view

    -- Called prior to the removal of scene's view ("sceneGroup").
    -- Insert code here to clean up the scene.
    -- Example: remove display objects, save state, etc.
    bckBtn:removeEventListener("touch", goBack )
    egon:removeEventListener("touch", moveEgon )

end



-- -------------------------------------------------------------------------------

-- Listener setup
scene:addEventListener( "create", scene )
scene:addEventListener( "show", scene )
scene:addEventListener( "hide", scene )
scene:addEventListener( "destroy", scene )

-- -------------------------------------------------------------------------------

return scene

Answer 1

當您的scene:show() ，您執行

timerSpawn = timer.performWithDelay(500, spawnObjects, 0 )

這將導致spawObjects無限期地每0.5秒調用一次（即，直到應用程序退出，或者計時器被取消或暫停）。 可以，但是當您返回該場景時，該行將再次執行，這將導致創建新的計時器，並且timeSpawn現在引用了該新計時器。 因此，現在您將有兩個計時器，大約每0.5秒觸發一次。 當您離開場景並再次返回時，您將得到3， timerSpawn被設置為引用新計時器的事實並不會停止舊計時器。 當場景隱藏時，您可能應該暫停timerSpawn ； 然后在show() ，僅應在不存在的情況下創建計時器：

function scene:show( event )
        ....
        ----------- Timers ------------
        countDownNumber = 10
        if countdownTimer == nil then
            countdownTimer = timer.performWithDelay( 1000, showCountDown, countNumber )
        else 
            timer.resume(countownTimer)
        end
        if timerSpawn == nil then
            timerSpawn = timer.performWithDelay(500, spawnObjects, 0 )
        else 
            timer.resume(timerSpawn)
        end
end

function scene:hide( event )
    ...
    if ( phase == "will" ) then
        timer.pause( timerSpawn )
        timer.pause( countdownTimer )
        -- NO: 
        -- timerSpawn = nil
        -- countdownTimer = nil
        ...
    end
end