我正在使用 Corona SDK 编写 iOS 应用程序。该应用程序已完成，但我发现了故事板的错误。打开几个不同的故事板场景并返回到这个场景后，我收到一个错误（见下文）。这似乎是随机的，我可以毫无问题地返回现场 4 或 5 次，但其他时候它可能会在我第一次返回时出现。我只能假设这取决于 Corona 对场景的内部处理，当内存使用量达到一定水平时，它会清除场景。
我收到的错误是：
Runtime error
/Users/**/contact.lua:124: attempt to call method 'insert' (a nil value)
stack traceback:
[C]: in function 'insert'
/Users/**/contact.lua:124: in function 'renderPage'
/Users/**/contact.lua:179: in function </Users/**/contact.lua:166>
产生此错误的代码如下。请注意，此代码在第一次打开时运行良好，并且在出现错误之前需要随机数次场景更改。
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--
-- contact.lua
--
-----------------------------------------------------------------------------------------
local storyboard = require( "storyboard" )
local scene = storyboard.newScene()
local widget = require( "widget" )
local tableView = require( "tableViewXL" )
-----------------------------------------------------------------------------------------
-- BEGINNING OF YOUR IMPLEMENTATION
--
-- NOTE: Code outside of listener functions (below) will only be executed once,
-- unless storyboard.removeScene() is called.
--
-----------------------------------------------------------------------------------------
-- Called when the scene's view does not exist:
function scene:createScene( event )
local group = self.view
local function openMenu()
transition.to( menu, { x = 0, time=600, transition=easing.outQuad } )
this_window = 'contact'
native.cancelWebPopup()
end
local openBtn = ui.newButton{
defaultSrc = 'images/menu.png',
defaultX = 29,
defaultY = 29,
overSrc = 'images/menu.png',
overX = 29,
overY = 29,
overAlpha = .5,
onEvent = openMenu,
text = "",
size = 14,
textColor = { 138, 173, 189, 255 },
font = system.nativeFont,
emboss = false,
id = "Button",
}
openBtn.x = 28; openBtn.y = 28
-- add background and logout button
local bg = display.newImageRect( "images/background.png", 320, 480 )
bg:setReferencePoint( display.TopLeftReferencePoint )
bg.x = 0; bg.y = 0;
-- Date
local date = txt.newEmbossed(os.date("%d/%m/%y"), 10, 60, native.systemFontBold, 12)
date:setTextColor( 55, 96, 127 ) -- blue
date:setReferencePoint( display.CenterReferencePoint )
date.x = 280
date.y = 84
-- Title
local title = txt.new( "Contact", 17, 72, 'Georgia', 20 )
title:setTextColor( 71, 24, 76 )
-- Called when the API is able to return user info (fb page, twitter, etc)
function renderPage( data )
local textAddress = txt.new( data.address, 17, 120, native.systemFont, 14, display.TopLeftReferencePoint, 300, 200 )
textAddress:setTextColor( 0, 0, 0 )
local phoneBar = display.newImageRect( "images/contact/phoneBar.png", 296, 24 )
phoneBar.x = (display.contentWidth * 0.5); phoneBar.y = 230
local phoneText = txt.new( data.phone, 20, 222, native.systemFont, 12, display.TopLeftReferencePoint )
phoneText:setTextColor( 70, 24, 72 )
local emailBar = display.newImageRect( "images/contact/emailBar.png", 296, 24 )
emailBar.x = (display.contentWidth * 0.5); emailBar.y = 260
local emailText = txt.new( data.email, 20, 252, native.systemFont, 12, display.TopLeftReferencePoint )
emailText:setTextColor( 70, 24, 72 )
local twitterBar = display.newImageRect( "images/contact/twitterBar.png", 296, 24 )
twitterBar.x = (display.contentWidth * 0.5); twitterBar.y = 290
local twitterText = txt.new( 'Twitter - @'.. data.twitter, 20, 282, native.systemFont, 12, display.TopLeftReferencePoint )
twitterText:setTextColor( 70, 24, 72 )
local facebookBar = display.newImageRect( "images/contact/facebookBar.png", 296, 24 )
facebookBar.x = (display.contentWidth * 0.5); facebookBar.y = 320
local facebookText = txt.new( 'Facebook', 20, 312, native.systemFont, 12, display.TopLeftReferencePoint )
facebookText:setTextColor( 70, 24, 72 )
local function phoneTouch( event )
if ( event.phase == "ended" ) then
system.openURL( "tel:".. data.phone )
end
end
local function emailTouch( event )
if ( event.phase == "ended" ) then
system.openURL( "mailto:".. data.email )
end
end
local function twitterTouch( event )
if ( event.phase == "ended" ) then
system.openURL( "https://twitter.com/intent/user?screen_name=".. data.twitter )
end
end
local function facebookTouch( event )
if ( event.phase == "ended" ) then
system.openURL( "fb://profile/".. data.facebook )
end
end
phoneBar:addEventListener( 'touch', phoneTouch )
phoneText:addEventListener( 'touch', phoneTouch )
emailBar:addEventListener( 'touch', emailTouch )
emailText:addEventListener( 'touch', emailTouch )
twitterBar:addEventListener( 'touch', twitterTouch )
twitterText:addEventListener( 'touch', twitterTouch )
facebookBar:addEventListener( 'touch', facebookTouch )
facebookText:addEventListener( 'touch', facebookTouch )
print ( textAddress )
group:insert( textAddress )
group:insert( phoneBar )
group:insert( phoneText )
group:insert( emailBar )
group:insert( emailText )
group:insert( twitterBar )
group:insert( twitterText )
group:insert( facebookBar )
group:insert( facebookText )
phoneText:toFront()
emailText:toFront()
twitterText:toFront()
facebookText:toFront()
-- Add the map
-- Load map template from a file
local path = system.pathForFile( "map_template.html", system.ResourceDirectory )
local file = io.open( path, "r" )
local mapTemplate = file:read( "*a" )
io.close( file )
-- Add in our address and write to another file
address = data.address1
if(data.address2 == '' and data.address2 ~= '') then address = address .. ', ' .. data.address2 end
if(data.citytown == '' and data.citytown ~= '') then address = address .. ', ' .. data.citytown end
if(data.county == '' and data.county ~= '') then address = address .. ', ' .. data.county end
if(data.postcode == '' and data.postcode ~= '') then address = address .. ', ' .. data.postcode end
mapTemplate = string.gsub( mapTemplate, "||ADDRESS||", address )
-- Now save it to a local file
local path = system.pathForFile( "map.html", system.DocumentsDirectory )
local file = io.open( path, "w" )
file:write( mapTemplate )
io.close( file )
local options = { hasBackground=false, baseUrl=system.DocumentsDirectory, urlRequest=listener }
native.showWebPopup( 0, 345, display.contentWidth, 130, "map.html", options )
end
function api.networkListener( event )
native.setActivityIndicator( false )
if ( event.isError ) then
native.showAlert( "Error", "Sorry, there was a problem communicating with the server.", {"Ok"} )
else
json = require "json"
local response = json.decode( event.response )
if(response.error) then
native.showAlert( "Error", response.error, {"Ok"} )
else
data = response
renderPage( data )
end
end
return event.response
end
native.setActivityIndicator( true )
api.request( 'users/me', "GET" )
-- all objects must be added to group (e.g. self.view)
group:insert( bg )
group:insert( date )
group:insert( title )
group:insert( openBtn )
end
-- Called immediately after scene has moved onscreen:
function scene:enterScene( event )
local group = self.view
end
-- Called when scene is about to move offscreen:
function scene:exitScene( event )
local group = self.view
-- INSERT code here (e.g. stop timers, remove listenets, unload sounds, etc.)
native.cancelWebPopup()
end
-- If scene's view is removed, scene:destroyScene() will be called just prior to:
function scene:destroyScene( event )
local group = self.view
-- INSERT code here (e.g. remove listeners, remove widgets, save state variables, etc.)
native.cancelWebPopup()
end
-----------------------------------------------------------------------------------------
-- END OF YOUR IMPLEMENTATION
-----------------------------------------------------------------------------------------
-- "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 whenever 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
当另一个场景打开时，我尝试清除这个场景。打印时group或textAddress两者都是表格，正如预期的那样。