tips
1：Don’t use __super in
C++ to instead super in objc. The keyworkd __super is only recognized by VC++, but can not compiled by GCC. So you had better to call the name of parent class, CCLayer::init()
2：All the gaming elements in cocos2d-x, such as sprite, layer, scene, label, action, are allocated in the heap. So we must
call their methods by “->”
3：The return type of init method is “bool” now. There’s
no keyword “id” in cpp, so the methods returning “id” is translated to a object pointer or bool.