Issue Reproduce Steps

There is a widget on scene, and the widget will set value in a customised Runtime Event Listener:

• If NO switch between scenes, the issue will not happen
• If switch between scenes, then dispatch the customised Runtime Event Listener, this error will happen: "attempt to perform arithmetic on field 'x' (a nil value)"

How to fix

• If you add the customised Runtime Event Listener like this:

Runtime:addEventListener("customisedEventListener", scene)

• Then you need to remove the customised Runtime Event Listener when scene is destroyed like this:

-- destroy()

function scene:destroy( event )
  local sceneGroup = self.view
  -- Code here runs prior to the removal of scene's view
  Runtime:removeEventListener("customisedEventListener", scene)
end

Problem is solved!

问题复现

在场景上有这么一个控件，这个控件在一个自定义的运行时事件监听中会被改变值：

• 如果不切换场景，则问题不会出现
• 如果切换场景后，然后触发这个自定义的运行时事件监听，则会出现如下问题："attempt to perform arithmetic on field 'x' (a nil value)"

修复方法

• 如果你的自定义运行时事件监听如下所示：

Runtime:addEventListener("customisedEventListener", scene)

• 那么需要在场景销毁时移除这个自定义运行时事件监听，如下所示

-- destroy()

function scene:destroy( event )
  local sceneGroup = self.view
  -- Code here runs prior to the removal of scene's view
  Runtime:removeEventListener("customisedEventListener", scene)
end

问题解决啦！