Hello everyone,
The app seems to be working fine the first time I go into the scene_game and start playing it. Once a player loses and sees the game over message, they go back to the scene_menu and then back to scene_game. The gameplay is fine but when they hit the object, instead of it showing the game over message, it shows this error. Looking forward to your replies.
It would be really helpful if you posed the relevant code. Please use the blue <> button in the edit bar to paste your code in.
In the mean time ask yourself why whatever the object is on line 100 that your attempting to remove and event listener doesn’t exist.
Rob
I apologize, I had thought I already posted my code. Here is my code
local composer = require( "composer" ) local scene = composer.newScene() local widget = require( "widget" ) local physics = require("physics") physics.start() physics.setGravity(0,0) -- ----------------------------------------------------------------------------------------------------------------- -- All code outside of the listener functions will only be executed ONCE unless "composer.removeScene()" is called. -- ----------------------------------------------------------------------------------------------------------------- -- local forward references should go here -- ------------------------------------------------------------------------------- -- "scene:create()" function scene:create( event ) -- Initialize the scene here. -- Example: add display objects to "sceneGroup", add touch listeners, etc. local sceneGroup = self.view local backgroundMusic = audio.loadStream("music/bgmusic.wav") local CarCrash = audio.loadStream("music/crash.wav") local PassbyCar = audio.loadStream("music/car.wav") -- The following variables are known as forward declares. We'll create some for the player, enemy, lanes and establish default values. local lanes = {} -- create a table called lanes local playerCar -- a variable for the player car local laneID = 1 -- a variable for the land id local enemyCars = {} -- a table to hold the enemy cars local enemyCounter = 1 -- start the enemy counter at 1 to keep track of the enemy cars local sendEnemyFrequency = 2500 -- defines how often to send enemy cars local tmrToSendCars -- a variable to hold a reference to the timer of sending cars local playerScore = 0 -- start the player score at 0 local playerScoreText -- an object to hold the score text object -- This function will increment the player score by 1. This function is called when the transition for the enemy car is complete and is off screen. local function incrementScore() playerScore = playerScore + 1 -- add playerScore by 1 playerScoreText.text = "Score: "..playerScore -- update the on screen text end -- moveCar will respond to the touch event on the lanes local function moveCar(event) if(event.phase == "ended") then laneID = event.target.id -- grab the lane id which will be 1, 2, or 3 transition.to(playerCar, {x=lanes[laneID].x,time=25}) -- move the player car to the appropriate lane return true -- to indicate a successful touch event, return true end end -- sendEnemyCar is where the magic happens. This function will send enemy cars from the top of the screen to the bottom of the screen. local function sendEnemyCar() enemyCars[enemyCounter] = display.newImageRect(sceneGroup, "images/enemyCar"..math.random(1,3)..".png", 50, 100) -- create a enemy car and grab a random enemy car image enemyCars[enemyCounter].x = lanes[math.random(1,#lanes)].x -- place the car on a random lane if(math.random(1,2) == 1) then enemyCars[enemyCounter].x = lanes[laneID].x; end -- 50% of the time, place the enemy car on the player car lane. enemyCars[enemyCounter].y = -125 -- place the enemy off screen at the top enemyCars[enemyCounter]:scale(1,-1) -- rotate the cars so they are facing down physics.addBody(enemyCars[enemyCounter]) -- add a physics body to enemy cars enemyCars[enemyCounter].bodyType = "kinematic" -- make the bodies kinematic transition.to(enemyCars[enemyCounter], {y=display.contentHeight+enemyCars[enemyCounter].height+20, time=math.random(2250,3000), onComplete=function(self) display.remove(self); incrementScore(); end}) -- a transition that moves the enemy car towards the bottom of the screen. On completion, the enemy car object is removed from the game. local PassbyCarChannel = audio.play(PassbyCar,{channel=3}) enemyCounter = enemyCounter + 1 -- increase enemy counter by one for tracking if(enemyCounter%2 == 0) then -- every other car, increase the speed of enemy frequency sendEnemyFrequency = sendEnemyFrequency - 200 -- deduct the frequency by 200ms if(sendEnemyFrequency \< 800) then sendEnemyFrequency = 800; end -- cap the send enemy frequency to 800 timer.cancel(tmrToSendCars) -- cancel the timer of sending cars tmrToSendCars = timer.performWithDelay(sendEnemyFrequency, sendEnemyCar, 0) -- recreate the time to send cars with update frequency end end -- Allow the player to return to the menu local function onMenu() composer.gotoScene("scene\_menu", "slideRight") -- move player to menu local backgroundMusicChannel = audio.play(backgroundMusic,{channel=1}) end -- local function onPlayAgain() -- composer.gotoScene("scene\_playagain", "fade") -- move player to menu -- end -- This is the global collision scene. There are several ways to handle collisions and this is only one method. I felt this was the easiest for learning purposes. local function onGlobalCollision(event) if(event.phase == "began") then -- when the enemy car collides into the player car, this if/then statement will be true local CarCrashChannel = audio.play(CarCrash,{channel=2}) -- stop the game transition.pause() timer.cancel(tmrToSendCars) physics.pause() -- remove event listeners from all lanes for i=1,3 do lanes[i]:removeEventListener("touch", moveCar) end local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight) -- display an opaque background graphic for some game over polish gameOverBackground.x = display.contentCenterX gameOverBackground.y = display.contentCenterY gameOverBackground:setFillColor(0) gameOverBackground.alpha = 0.5 -- Create a text object that will display game over text local gameOverText = display.newText( sceneGroup, "Game Over!", 100, 200, native.systemFontBold, 36 ) gameOverText.x = display.contentCenterX gameOverText.y = 150 gameOverText:setFillColor( 1, 1, 1 ) -- create a button that allows the player to return to the local menu = widget.newButton { width = 220, height = 100, defaultFile = "images/btn-blank.png", overFile = "images/btn-blank.png", label = "Menu", font = system.defaultFontBold, fontSize = 32, labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, onEvent = onMenu } menu.x = display.contentCenterX menu.y = gameOverText.y + 100 sceneGroup:insert(menu) -- local playagain = widget.newButton { -- width = 220, -- height = 100, -- defaultFile = "images/btn-blank.png", -- overFile = "images/btn-blank.png", -- label = "Play Again", -- font = system.defaultFontBold, -- fontSize = 32, -- labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, -- onEvent = onPlayAgain -- } -- playagain.x = display.contentCenterX -- playagain.y = gameOverText.y + 200 -- sceneGroup:insert(playagain) end end local background = display.newImageRect(sceneGroup, "images/background.png", 475, 713) -- create the background image object background.x = display.contentCenterX -- place the graphic in the center of the x-axis background.y = display.contentCenterY -- place the graphic in the center of the y-axis for i=1,3 do -- loop 3 times to create 3 lanes for our game lanes[i] = display.newImageRect(sceneGroup, "images/lane.png", 79, 713) lanes[i].x = (display.contentCenterX - 79\*2) + (i\*80) lanes[i].y = display.contentCenterY lanes[i].id = i lanes[i]:addEventListener("touch", moveCar) -- add an event listener to the lanes that will respond to touch events. end playerScoreText = display.newText(sceneGroup, "Score: "..playerScore, 0, 0, native.systemFont, 36) -- Create a text object that will display the player score playerScoreText.x = display.contentCenterX playerScoreText.y = 25 playerCar = display.newImageRect(sceneGroup, "images/playerCar.png", 50, 100) -- create the player car image object playerCar.anchorY = 1 -- set the anchor point to 1 which is the bottom of the graphic playerCar.x = lanes[1].x -- put the player car on the first lane playerCar.y = display.contentHeight -- place the car at the bottom of the screen physics.addBody(playerCar) -- add a physics body to the car playerCar.bodyType = "dynamic" -- make the car a dynamic body type tmrToSendCars = timer.performWithDelay(sendEnemyFrequency, sendEnemyCar, 0) -- start a timer to send cards. A 0 means run forever Runtime:addEventListener( "collision", onGlobalCollision ) -- create a global event listener to listen for any collision. 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. 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, etc. 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. end -- ------------------------------------------------------------------------------- -- Listener setup scene:addEventListener( "create", scene ) scene:addEventListener( "show", scene ) scene:addEventListener( "hide", scene ) scene:addEventListener( "destroy", scene ) -- ------------------------------------------------------------------------------- return sceneYou are most likely falling victim to trying to remove things in the middle of the collision happening. Perhaps you should do something like this:
timer.performWithDelay(10, function() for i=1,3 do if lanes[i] and lanes[i].removeEventListener then lanes[i]:removeEventListener("touch", moveCar) end end end)I tried your solution out but after doing this, it is now giving me a new error.
I suspect your new line 106 is:
local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight)
Argument #1 to display.newRect() is expected to be something called a proxy, but it’s nil.
What is argument #1? It’s “sceneGroup”. It’s expecting a display.newGroup() object to be passed in as the first parameter and not nil. Normally in a composer scene, for the scene event functions (scene:create(), scene:show(), etc.) you create a variable “sceneGroup” that is a pointer to self.view. self.view is the same as scene.view. But this group is only scoped to those functions.
Since line 106 is not inside a scene function where you’ve defined sceneGroup.
Your solution is to add just after line 89
local function onGlobalCollision(event) local sceneGroup = scene.viewThat was a great informational post on what this error meant. Now instead of it expecting a proxy, it is stating that it is expecting a number. I don’t really know how to solve this either. Thank you Rob so much for your help. You are helping me understand this situation much better as I am continuing to troubleshoot this issue.
Can you post your current error message and the code around it?
Rob
Sure here is the code and the error message below:
local function onGlobalCollision(event) local sceneGroup = scene.view if(event.phase == "began") then -- when the enemy car collides into the player car, this if/then statement will be true local CarCrashChannel = audio.play(CarCrash,{channel=2}) -- stop the game transition.pause() timer.cancel(tmrToSendCars) physics.pause() -- remove event listeners from all lanes timer.performWithDelay(10, function() for i=1,3 do if lanes[i] and lanes[i].removeEventListener then lanes[i]:removeEventListener("touch", moveCar) end end end) local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight) -- display an opaque background graphic for some game over polish gameOverBackground.x = display.contentCenterX gameOverBackground.y = display.contentCenterY gameOverBackground:setFillColor(0) gameOverBackground.alpha = 0.5 -- Create a text object that will display game over text local gameOverText = display.newText( sceneGroup, "Game Over!", 100, 200, native.systemFontBold, 36 ) gameOverText.x = display.contentCenterX gameOverText.y = 150 gameOverText:setFillColor( 1, 1, 1 ) -- create a button that allows the player to return to the local menu = widget.newButton { width = 220, height = 100, defaultFile = "images/btn-blank.png", overFile = "images/btn-blank.png", label = "Menu", font = system.defaultFontBold, fontSize = 32, labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, onEvent = onMenu } menu.x = display.contentCenterX menu.y = gameOverText.y + 100 sceneGroup:insert(menu)
Stick this around line 107:
print( type( scene.view ) )
Run the app and see what messages show up in your console log. Copy and paste your console log run here.
Rob
Hello Rob,
I managed to solve the issue. Apparently by adding Runtime:removeEventListener( “collision”, onGlobalCollision )’ after physics.pause() in the function onGlobalCollision will fix the issue in my case. This error was occurring because the global collision was not removed when leaving the game to go back to the menu. Thank you once again for the help!
It would be really helpful if you posed the relevant code. Please use the blue <> button in the edit bar to paste your code in.
In the mean time ask yourself why whatever the object is on line 100 that your attempting to remove and event listener doesn’t exist.
Rob
I apologize, I had thought I already posted my code. Here is my code
local composer = require( "composer" ) local scene = composer.newScene() local widget = require( "widget" ) local physics = require("physics") physics.start() physics.setGravity(0,0) -- ----------------------------------------------------------------------------------------------------------------- -- All code outside of the listener functions will only be executed ONCE unless "composer.removeScene()" is called. -- ----------------------------------------------------------------------------------------------------------------- -- local forward references should go here -- ------------------------------------------------------------------------------- -- "scene:create()" function scene:create( event ) -- Initialize the scene here. -- Example: add display objects to "sceneGroup", add touch listeners, etc. local sceneGroup = self.view local backgroundMusic = audio.loadStream("music/bgmusic.wav") local CarCrash = audio.loadStream("music/crash.wav") local PassbyCar = audio.loadStream("music/car.wav") -- The following variables are known as forward declares. We'll create some for the player, enemy, lanes and establish default values. local lanes = {} -- create a table called lanes local playerCar -- a variable for the player car local laneID = 1 -- a variable for the land id local enemyCars = {} -- a table to hold the enemy cars local enemyCounter = 1 -- start the enemy counter at 1 to keep track of the enemy cars local sendEnemyFrequency = 2500 -- defines how often to send enemy cars local tmrToSendCars -- a variable to hold a reference to the timer of sending cars local playerScore = 0 -- start the player score at 0 local playerScoreText -- an object to hold the score text object -- This function will increment the player score by 1. This function is called when the transition for the enemy car is complete and is off screen. local function incrementScore() playerScore = playerScore + 1 -- add playerScore by 1 playerScoreText.text = "Score: "..playerScore -- update the on screen text end -- moveCar will respond to the touch event on the lanes local function moveCar(event) if(event.phase == "ended") then laneID = event.target.id -- grab the lane id which will be 1, 2, or 3 transition.to(playerCar, {x=lanes[laneID].x,time=25}) -- move the player car to the appropriate lane return true -- to indicate a successful touch event, return true end end -- sendEnemyCar is where the magic happens. This function will send enemy cars from the top of the screen to the bottom of the screen. local function sendEnemyCar() enemyCars[enemyCounter] = display.newImageRect(sceneGroup, "images/enemyCar"..math.random(1,3)..".png", 50, 100) -- create a enemy car and grab a random enemy car image enemyCars[enemyCounter].x = lanes[math.random(1,#lanes)].x -- place the car on a random lane if(math.random(1,2) == 1) then enemyCars[enemyCounter].x = lanes[laneID].x; end -- 50% of the time, place the enemy car on the player car lane. enemyCars[enemyCounter].y = -125 -- place the enemy off screen at the top enemyCars[enemyCounter]:scale(1,-1) -- rotate the cars so they are facing down physics.addBody(enemyCars[enemyCounter]) -- add a physics body to enemy cars enemyCars[enemyCounter].bodyType = "kinematic" -- make the bodies kinematic transition.to(enemyCars[enemyCounter], {y=display.contentHeight+enemyCars[enemyCounter].height+20, time=math.random(2250,3000), onComplete=function(self) display.remove(self); incrementScore(); end}) -- a transition that moves the enemy car towards the bottom of the screen. On completion, the enemy car object is removed from the game. local PassbyCarChannel = audio.play(PassbyCar,{channel=3}) enemyCounter = enemyCounter + 1 -- increase enemy counter by one for tracking if(enemyCounter%2 == 0) then -- every other car, increase the speed of enemy frequency sendEnemyFrequency = sendEnemyFrequency - 200 -- deduct the frequency by 200ms if(sendEnemyFrequency \< 800) then sendEnemyFrequency = 800; end -- cap the send enemy frequency to 800 timer.cancel(tmrToSendCars) -- cancel the timer of sending cars tmrToSendCars = timer.performWithDelay(sendEnemyFrequency, sendEnemyCar, 0) -- recreate the time to send cars with update frequency end end -- Allow the player to return to the menu local function onMenu() composer.gotoScene("scene\_menu", "slideRight") -- move player to menu local backgroundMusicChannel = audio.play(backgroundMusic,{channel=1}) end -- local function onPlayAgain() -- composer.gotoScene("scene\_playagain", "fade") -- move player to menu -- end -- This is the global collision scene. There are several ways to handle collisions and this is only one method. I felt this was the easiest for learning purposes. local function onGlobalCollision(event) if(event.phase == "began") then -- when the enemy car collides into the player car, this if/then statement will be true local CarCrashChannel = audio.play(CarCrash,{channel=2}) -- stop the game transition.pause() timer.cancel(tmrToSendCars) physics.pause() -- remove event listeners from all lanes for i=1,3 do lanes[i]:removeEventListener("touch", moveCar) end local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight) -- display an opaque background graphic for some game over polish gameOverBackground.x = display.contentCenterX gameOverBackground.y = display.contentCenterY gameOverBackground:setFillColor(0) gameOverBackground.alpha = 0.5 -- Create a text object that will display game over text local gameOverText = display.newText( sceneGroup, "Game Over!", 100, 200, native.systemFontBold, 36 ) gameOverText.x = display.contentCenterX gameOverText.y = 150 gameOverText:setFillColor( 1, 1, 1 ) -- create a button that allows the player to return to the local menu = widget.newButton { width = 220, height = 100, defaultFile = "images/btn-blank.png", overFile = "images/btn-blank.png", label = "Menu", font = system.defaultFontBold, fontSize = 32, labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, onEvent = onMenu } menu.x = display.contentCenterX menu.y = gameOverText.y + 100 sceneGroup:insert(menu) -- local playagain = widget.newButton { -- width = 220, -- height = 100, -- defaultFile = "images/btn-blank.png", -- overFile = "images/btn-blank.png", -- label = "Play Again", -- font = system.defaultFontBold, -- fontSize = 32, -- labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, -- onEvent = onPlayAgain -- } -- playagain.x = display.contentCenterX -- playagain.y = gameOverText.y + 200 -- sceneGroup:insert(playagain) end end local background = display.newImageRect(sceneGroup, "images/background.png", 475, 713) -- create the background image object background.x = display.contentCenterX -- place the graphic in the center of the x-axis background.y = display.contentCenterY -- place the graphic in the center of the y-axis for i=1,3 do -- loop 3 times to create 3 lanes for our game lanes[i] = display.newImageRect(sceneGroup, "images/lane.png", 79, 713) lanes[i].x = (display.contentCenterX - 79\*2) + (i\*80) lanes[i].y = display.contentCenterY lanes[i].id = i lanes[i]:addEventListener("touch", moveCar) -- add an event listener to the lanes that will respond to touch events. end playerScoreText = display.newText(sceneGroup, "Score: "..playerScore, 0, 0, native.systemFont, 36) -- Create a text object that will display the player score playerScoreText.x = display.contentCenterX playerScoreText.y = 25 playerCar = display.newImageRect(sceneGroup, "images/playerCar.png", 50, 100) -- create the player car image object playerCar.anchorY = 1 -- set the anchor point to 1 which is the bottom of the graphic playerCar.x = lanes[1].x -- put the player car on the first lane playerCar.y = display.contentHeight -- place the car at the bottom of the screen physics.addBody(playerCar) -- add a physics body to the car playerCar.bodyType = "dynamic" -- make the car a dynamic body type tmrToSendCars = timer.performWithDelay(sendEnemyFrequency, sendEnemyCar, 0) -- start a timer to send cards. A 0 means run forever Runtime:addEventListener( "collision", onGlobalCollision ) -- create a global event listener to listen for any collision. 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. 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, etc. 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. end -- ------------------------------------------------------------------------------- -- Listener setup scene:addEventListener( "create", scene ) scene:addEventListener( "show", scene ) scene:addEventListener( "hide", scene ) scene:addEventListener( "destroy", scene ) -- ------------------------------------------------------------------------------- return sceneYou are most likely falling victim to trying to remove things in the middle of the collision happening. Perhaps you should do something like this:
timer.performWithDelay(10, function() for i=1,3 do if lanes[i] and lanes[i].removeEventListener then lanes[i]:removeEventListener("touch", moveCar) end end end)I tried your solution out but after doing this, it is now giving me a new error.
I suspect your new line 106 is:
local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight)
Argument #1 to display.newRect() is expected to be something called a proxy, but it’s nil.
What is argument #1? It’s “sceneGroup”. It’s expecting a display.newGroup() object to be passed in as the first parameter and not nil. Normally in a composer scene, for the scene event functions (scene:create(), scene:show(), etc.) you create a variable “sceneGroup” that is a pointer to self.view. self.view is the same as scene.view. But this group is only scoped to those functions.
Since line 106 is not inside a scene function where you’ve defined sceneGroup.
Your solution is to add just after line 89
local function onGlobalCollision(event) local sceneGroup = scene.viewThat was a great informational post on what this error meant. Now instead of it expecting a proxy, it is stating that it is expecting a number. I don’t really know how to solve this either. Thank you Rob so much for your help. You are helping me understand this situation much better as I am continuing to troubleshoot this issue.
Can you post your current error message and the code around it?
Rob
Sure here is the code and the error message below:
local function onGlobalCollision(event) local sceneGroup = scene.view if(event.phase == "began") then -- when the enemy car collides into the player car, this if/then statement will be true local CarCrashChannel = audio.play(CarCrash,{channel=2}) -- stop the game transition.pause() timer.cancel(tmrToSendCars) physics.pause() -- remove event listeners from all lanes timer.performWithDelay(10, function() for i=1,3 do if lanes[i] and lanes[i].removeEventListener then lanes[i]:removeEventListener("touch", moveCar) end end end) local gameOverBackground = display.newRect(sceneGroup, 0, 0, display.actualContentWidth, display.actualContentHeight) -- display an opaque background graphic for some game over polish gameOverBackground.x = display.contentCenterX gameOverBackground.y = display.contentCenterY gameOverBackground:setFillColor(0) gameOverBackground.alpha = 0.5 -- Create a text object that will display game over text local gameOverText = display.newText( sceneGroup, "Game Over!", 100, 200, native.systemFontBold, 36 ) gameOverText.x = display.contentCenterX gameOverText.y = 150 gameOverText:setFillColor( 1, 1, 1 ) -- create a button that allows the player to return to the local menu = widget.newButton { width = 220, height = 100, defaultFile = "images/btn-blank.png", overFile = "images/btn-blank.png", label = "Menu", font = system.defaultFontBold, fontSize = 32, labelColor = { default={ 0, 0, 0 }, over={ 0, 0, 0, 0.5 } }, onEvent = onMenu } menu.x = display.contentCenterX menu.y = gameOverText.y + 100 sceneGroup:insert(menu)
Stick this around line 107:
print( type( scene.view ) )
Run the app and see what messages show up in your console log. Copy and paste your console log run here.
Rob