On the Level – Eskimo - Cocos2d-x by Example Beginner's Guide - page 330

static GameLayer* _instance = nullptr;
We can check, then, if the one instance of GameLayer is currently in memory
and instantiate it if necessary.
4. The scene transition to GameLayer will look, on the surface, to be exactly like
the regular kind of transition. So, in LevelSelectLayer , we have the follow-
ing:
auto newScene = TransitionMoveInR::create(0.2f,
GameLayer::scene(_firstIndex + i, _levelsCompleted));
Director::sharedDirector()->replaceScene(newScene);