cocos2dx 3.x 关于action的回调函数

auto bgPic = Sprite :: create( "StartGameBg.jpg" );
             bgPic ->setContentSize ( Size( 800.0f , 1246.0f));
             bgPic ->setPosition ( Vec2( visibleSize .width / 2 , - bgPic -> getContentSize(). height /2 + visibleSize . height));
             this -> addChild( bgPic );

             FiniteTimeAction * moveAction = EaseExponentialInOut:: create (MoveTo :: create( 6.0f , Vec2 (visibleSize . width / 2 ,bgPic -> getContentSize(). height / 2)));
             bgPic ->runAction ( Sequence:: create (
                         moveAction ,
                         CallFunc ::create ( CC_CALLBACK_0( GameStartScene ::buttonLogin , this )),
                         nullptr ));