stage:addChild question

Jacko

How can I check if sprite is on stage?

pie

stage:contains(child)

where child is the sprite you are looking for

Jacko

I want to remove sprite after click on button and that spite isnt on stage so do i have to check if stage:contains(child)?

pie

Check if it exists before removing it:

if mySprite then --remove mySprite end

Jacko

What about every time addChild befor removing.
stage:addChild(sprite)
stage:removeChild(sprite)
or its take memories?

pie

Everything takes memory, I wonder why you should add a sprite just to remove it

If it is because you can't access it, maybe the reason is because it is referenced as local, and stage is missing the reference to sprite.

Jacko

Its because it isnt on stage;)

pie

I'm missing why do you want to remove your sprite (which is not a child of stage) from stage.

you remove a sprite from its parent:
if its parent is stage, you remove it from stage,
if its parent is another sprite you remove it from the other sprite.

you can also try:

if sprite then sprite:removeFromParent() sprite = nil end

keszegh

you may be missing that there are two parallel structures for your objects, one is the hierarchy how they are added to the stage, the other is based on object oriented programming, and is not related to stage hierarchy, objects can exist without being added to the stage or whatever. in this hierarchy one object (or rather table in case of lua) can be a subtable of another, like
obj1=Sprite.new()
obj1.obj2=Sprite.new()
then you have two objects, obj1.obj2 is a subtable of obj1, but you can still build the stage hierarchy in any other way. thus in the stage it's possible to have
stage:addChild(obj1.obj2)
and obj1.obj2:addChild(obj1) and so in the stage obj1 is the child of obj1.obj2.

also if you don't add them to the stage, they still exist in the memory until you e.g. nil them e.g. obj1.obj2=nil will release obj1.obj2, but e.g. obj1=nil will release both of them as nothing will reference obj1.obj2 anymore).