Question

Can I detect all the visible sprites in a layer in order to use them.

Answer 1

Here i assume u r using Box2d with cocos2d

//here create ccsprite and add them to ur scene

while create body with bodydef

    bodydef.userData=ccspriteobject;

    for (b2Body* b = m_world->GetBodyList(); b; b = b->GetNext())
    {
        if (b->GetUserData() != NULL) {
        //if the userdata is not null then ur sprite

            CCSprite *actor = (CCSprite*)b->GetUserData();