Just a very quick question…
I have a scene (scene1) in my app that is only ever used once and non of the assets are reused either, so once composer has called the next scene I want to call composer.removeScene( “scene1” ) to free the memory that was used.
In the scene:destroy function for scene1 do I manually have to remove every display object from the scene and nil them, or is there an easier (and quicker) way? Or have I misunderstood it altogether?
If its native control then you will have to manually remove each individually. (I read it from the forum.)
However, i got the problem where i remove each native.textfield in exitScene, but the textfield still remains when next scene appears.
==========================================================
MY CODE:
function scene:exitScene( event )
if _textBox_Email then
_textBox_Email:removeEventListener( “userInput”, textListener_textBox_Email )
_textBox_Email:removeSelf()
_textBox_Email = nil
end
end
==========================================================
i did a print of the textfield’s value in exitScene and it returns nil which means it never hit the removeSelf part. But if I don’t do the checking it gives me the error:
?: in function ‘dispatchEvent’
?: in function ‘?’
?: in function ‘gotoScene’
Can someone teach me how to properly remove native control from current scene before go to next scene?
Thank you!
Do you have a scope error? Is it by any chance local to your enterScene() function?
I local them in createScene. I tried move them outside the function then it doesn’t work.
here is my entire code please take a look for me. Thank you! Appreciate your help Rob.
-Edwin
==============================================================================================
local storyboard = require( “storyboard” )
local scene = storyboard.newScene()
display.setDefault( “background”,100/255,200/255,200/255)
storyboard.removeAll()
– Called when the scene’s view does not exist:
function scene:createScene( event )
–DECLARE CONTROL
local json = require “json”
local dataURL = "http://goldendehon.com/durham/latest.php"
local _hiddenField_Email = “”
local _hiddenField_Password = “”
local _textBox_Email = native.newTextField( display.contentCenterX, display.contentCenterY-28, 280, 25 )
_textBox_Email.font = native.newFont( native.systemFont, 20 )
_textBox_Email.InputType = “email”
_textBox_Email.placeholder = “Email”
local _textBox_Password = native.newTextField( display.contentCenterX, display.contentCenterY, 280, 25 )
_textBox_Password.font = native.newFont( native.systemFont, 20 )
_textBox_Password.isSecure = true
_textBox_Password.placeholder = “Password”
local _button_SubmitLogin = display.newText( “Get Data”,display.contentCenterX,display.contentCenterY+35,“Helvetica”,48 )
–DECLARE FUNCTION
local function textListener_textBox_Email (event)
if ( event.phase == “submitted” or event.phase == “ended” ) then
_hiddenField_Email = event.target.text
end
end
local function textListener_textBox_Password (event)
if ( event.phase == “submitted” or event.phase == “ended” ) then
_hiddenField_Password = event.target.text
end
end
local options =
{
effect = “fade”,
time = 10000
--params = { var1 = “custom”, myVar = “another” }
}
–download data to temp file, and read from file
– load a text file and return it as a string
local function loadTextFile( filename, base )
– set default base dir if none specified
if not base then base = system.ResourceDirectory; end
local path = system.pathForFile( filename, base )
local contents
– io.open opens a file at path. returns nil if no file found
local file = io.open( path, “r” )
if file then
– read all contents of file into a string
contents = file:read( “*a” )
io.close( file ) – close the file after using it
end
return contents
end
local function getNewData()
if _hiddenField_Email == ‘’ or _hiddenField_Password == ‘’ then
native.showAlert( “Error”, “Please enter email and password!”, {“OK”})
else
local function newDataListener(event)
if (event.isError) then
print (“Error - no connection.”)
native.showAlert( “Error”, “Error - no connection.”, {“OK”})
else
local t = loadTextFile(“latest.txt”,system.TemporaryDirectory)
if t:sub(1,7) == "Error: " then
native.showAlert(“Error”,t,{“OK”})
else
t = json.decode( t )
if #t > 0 then
print ("Number of records: " … tostring(#t))
for v = 1, #t do
print (t[v][“BusinessName”])
end
else
print (“No new record found!”)
native.showAlert( “Error”, “No new record found!”, {“OK”})
end
storyboard.gotoScene( “controlPanel”, “slideLeft”,8000 )
end
end
end
–local settings = {username=“edwin@email.com”,password=“pword”}
local settings = {username=_hiddenField_Email ,password=_hiddenField_Password}
local params = {}
params.body = “u=” … settings.username … “&p=” … settings.password … “&q=select * from bizlicense order by PrimaryNAICSText asc”
network.download( dataURL, “POST”, newDataListener, params,“latest.txt”,system.TemporaryDirectory)
end
end
_button_SubmitLogin:addEventListener(“tap”,getNewData)
_textBox_Email:addEventListener( “userInput”, textListener_textBox_Email )
_textBox_Password:addEventListener( “userInput”, textListener_textBox_Password)
end
– Called immediately after scene has moved onscreen:
function scene:enterScene( event )
end
– Called when scene is about to move offscreen:
function scene:exitScene( event )
if _textBox_Email then
print(“Exiting…”)
_textBox_Email:removeEventListener( “userInput”, textListener_textBox_Email )
_textBox_Email:removeSelf()
_textBox_Email = nil
else
print(“Not Exiting…”)
end
native.setKeyboardFocus(nil)
–_textBox_Password
–_button_SubmitLogin
end
– Called prior to the removal of scene’s “view” (display group)
function scene:destroyScene( event )
end
– “createScene” event is dispatched if scene’s view does not exist
scene:addEventListener( “createScene”, scene )
– “enterScene” event is dispatched whenever scene transition has finished
scene:addEventListener( “enterScene”, scene )
– “exitScene” event is dispatched before next scene’s transition begins
scene:addEventListener( “exitScene”, scene )
– “destroyScene” event is dispatched before view is unloaded, which can be
– automatically unloaded in low memory situations, or explicitly via a call to
– storyboard.purgeScene() or storyboard.removeScene().
scene:addEventListener( “destroyScene”, scene )
return scene
==============================================================================================
Move these two lines outside of createScene just after or before the storyboard.removeAll()
local _hiddenField_Email = “”
local _hiddenField_Password = “”
Then you should be fine.
Rob
Thanks Rob for your prompt reply.
So i tried move the _hiddenFIeld out after the storyboard.removeAll(), nothing changes.
However, if I moved out all the local declaration outside the createScene after storyboard.removeAll() then it works.
Does it mean that I always declare controls and functions outside the function scene:xxxxx and only put the :addEventListener to the scene i want to use it??
-Edwin
You need to understand how code blocks work with local. If you have a function:
function doSomething()
local myVariable = 10
print(myVariable)
end
doSomething()
The function runs, creates a variable named myVariable that only doSomething() knows about. If you did this:
function doSomething()
local myVariable = 10
end
doSomething()
print(myVariable)
In this case, myVariable has not been defined, so it tries to access a global variable named myVariable which is nil.
In your case, it’s perfectly fine to have things local inside of createScene() as long as you understand that they can only be seen within createScene.
If you need a variable that both createScene() and exitScene() (or enterScene() ) need, then you need to make sure they are scoped either at a higher block (i.e. putting them at the top) which creates something called an *upvalue*, or add it to the scene’s object as a member.
Upvalues are okay, but there are a limit of 60 per module. You could also in createScene do:
self.myVariable = “something”
Then in exitScene you would have self.myVariable available to you as well. The only draw back here is you have to avoid using names that would stomp on existing things in the scene.object. If you’re going to go this route, the suggestion is to use a table called “state” and then add your members there:
self.state = {}
self.state.myVariable = “something”
This tutorial might be helpful:
http://omnigeek.robmiracle.com/2011/10/14/understanding-scope-for-beginning-programmers/
Rob
Thank you Rob!! Appreciate your help!!!
-Edwin
If its native control then you will have to manually remove each individually. (I read it from the forum.)
However, i got the problem where i remove each native.textfield in exitScene, but the textfield still remains when next scene appears.
==========================================================
MY CODE:
function scene:exitScene( event )
if _textBox_Email then
_textBox_Email:removeEventListener( “userInput”, textListener_textBox_Email )
_textBox_Email:removeSelf()
_textBox_Email = nil
end
end
==========================================================
i did a print of the textfield’s value in exitScene and it returns nil which means it never hit the removeSelf part. But if I don’t do the checking it gives me the error:
?: in function ‘dispatchEvent’
?: in function ‘?’
?: in function ‘gotoScene’
Can someone teach me how to properly remove native control from current scene before go to next scene?
Thank you!
Do you have a scope error? Is it by any chance local to your enterScene() function?
I local them in createScene. I tried move them outside the function then it doesn’t work.
here is my entire code please take a look for me. Thank you! Appreciate your help Rob.
-Edwin
==============================================================================================
local storyboard = require( “storyboard” )
local scene = storyboard.newScene()
display.setDefault( “background”,100/255,200/255,200/255)
storyboard.removeAll()
– Called when the scene’s view does not exist:
function scene:createScene( event )
–DECLARE CONTROL
local json = require “json”
local dataURL = "http://goldendehon.com/durham/latest.php"
local _hiddenField_Email = “”
local _hiddenField_Password = “”
local _textBox_Email = native.newTextField( display.contentCenterX, display.contentCenterY-28, 280, 25 )
_textBox_Email.font = native.newFont( native.systemFont, 20 )
_textBox_Email.InputType = “email”
_textBox_Email.placeholder = “Email”
local _textBox_Password = native.newTextField( display.contentCenterX, display.contentCenterY, 280, 25 )
_textBox_Password.font = native.newFont( native.systemFont, 20 )
_textBox_Password.isSecure = true
_textBox_Password.placeholder = “Password”
local _button_SubmitLogin = display.newText( “Get Data”,display.contentCenterX,display.contentCenterY+35,“Helvetica”,48 )
–DECLARE FUNCTION
local function textListener_textBox_Email (event)
if ( event.phase == “submitted” or event.phase == “ended” ) then
_hiddenField_Email = event.target.text
end
end
local function textListener_textBox_Password (event)
if ( event.phase == “submitted” or event.phase == “ended” ) then
_hiddenField_Password = event.target.text
end
end
local options =
{
effect = “fade”,
time = 10000
--params = { var1 = “custom”, myVar = “another” }
}
–download data to temp file, and read from file
– load a text file and return it as a string
local function loadTextFile( filename, base )
– set default base dir if none specified
if not base then base = system.ResourceDirectory; end
local path = system.pathForFile( filename, base )
local contents
– io.open opens a file at path. returns nil if no file found
local file = io.open( path, “r” )
if file then
– read all contents of file into a string
contents = file:read( “*a” )
io.close( file ) – close the file after using it
end
return contents
end
local function getNewData()
if _hiddenField_Email == ‘’ or _hiddenField_Password == ‘’ then
native.showAlert( “Error”, “Please enter email and password!”, {“OK”})
else
local function newDataListener(event)
if (event.isError) then
print (“Error - no connection.”)
native.showAlert( “Error”, “Error - no connection.”, {“OK”})
else
local t = loadTextFile(“latest.txt”,system.TemporaryDirectory)
if t:sub(1,7) == "Error: " then
native.showAlert(“Error”,t,{“OK”})
else
t = json.decode( t )
if #t > 0 then
print ("Number of records: " … tostring(#t))
for v = 1, #t do
print (t[v][“BusinessName”])
end
else
print (“No new record found!”)
native.showAlert( “Error”, “No new record found!”, {“OK”})
end
storyboard.gotoScene( “controlPanel”, “slideLeft”,8000 )
end
end
end
–local settings = {username=“edwin@email.com”,password=“pword”}
local settings = {username=_hiddenField_Email ,password=_hiddenField_Password}
local params = {}
params.body = “u=” … settings.username … “&p=” … settings.password … “&q=select * from bizlicense order by PrimaryNAICSText asc”
network.download( dataURL, “POST”, newDataListener, params,“latest.txt”,system.TemporaryDirectory)
end
end
_button_SubmitLogin:addEventListener(“tap”,getNewData)
_textBox_Email:addEventListener( “userInput”, textListener_textBox_Email )
_textBox_Password:addEventListener( “userInput”, textListener_textBox_Password)
end
– Called immediately after scene has moved onscreen:
function scene:enterScene( event )
end
– Called when scene is about to move offscreen:
function scene:exitScene( event )
if _textBox_Email then
print(“Exiting…”)
_textBox_Email:removeEventListener( “userInput”, textListener_textBox_Email )
_textBox_Email:removeSelf()
_textBox_Email = nil
else
print(“Not Exiting…”)
end
native.setKeyboardFocus(nil)
–_textBox_Password
–_button_SubmitLogin
end
– Called prior to the removal of scene’s “view” (display group)
function scene:destroyScene( event )
end
– “createScene” event is dispatched if scene’s view does not exist
scene:addEventListener( “createScene”, scene )
– “enterScene” event is dispatched whenever scene transition has finished
scene:addEventListener( “enterScene”, scene )
– “exitScene” event is dispatched before next scene’s transition begins
scene:addEventListener( “exitScene”, scene )
– “destroyScene” event is dispatched before view is unloaded, which can be
– automatically unloaded in low memory situations, or explicitly via a call to
– storyboard.purgeScene() or storyboard.removeScene().
scene:addEventListener( “destroyScene”, scene )
return scene
==============================================================================================
Move these two lines outside of createScene just after or before the storyboard.removeAll()
local _hiddenField_Email = “”
local _hiddenField_Password = “”
Then you should be fine.
Rob
Thanks Rob for your prompt reply.
So i tried move the _hiddenFIeld out after the storyboard.removeAll(), nothing changes.
However, if I moved out all the local declaration outside the createScene after storyboard.removeAll() then it works.
Does it mean that I always declare controls and functions outside the function scene:xxxxx and only put the :addEventListener to the scene i want to use it??
-Edwin
You need to understand how code blocks work with local. If you have a function:
function doSomething()
local myVariable = 10
print(myVariable)
end
doSomething()
The function runs, creates a variable named myVariable that only doSomething() knows about. If you did this:
function doSomething()
local myVariable = 10
end
doSomething()
print(myVariable)
In this case, myVariable has not been defined, so it tries to access a global variable named myVariable which is nil.
In your case, it’s perfectly fine to have things local inside of createScene() as long as you understand that they can only be seen within createScene.
If you need a variable that both createScene() and exitScene() (or enterScene() ) need, then you need to make sure they are scoped either at a higher block (i.e. putting them at the top) which creates something called an *upvalue*, or add it to the scene’s object as a member.
Upvalues are okay, but there are a limit of 60 per module. You could also in createScene do:
self.myVariable = “something”
Then in exitScene you would have self.myVariable available to you as well. The only draw back here is you have to avoid using names that would stomp on existing things in the scene.object. If you’re going to go this route, the suggestion is to use a table called “state” and then add your members there:
self.state = {}
self.state.myVariable = “something”
This tutorial might be helpful:
http://omnigeek.robmiracle.com/2011/10/14/understanding-scope-for-beginning-programmers/
Rob
Thank you Rob!! Appreciate your help!!!
-Edwin