Cocos creator detect the moment when scene is activated

hello

I have some question about cocos creator api.

Recently I recognize that if I change my cursor to other tab game is stopped.

But my game is using server it is necessary to sync time with server.

so I try to reqeust server a message to sync time when I come back to my game tab again.

But I couldn’t found any method that notice me my game status change to active from deactive.

Is there any one who know about it?

All I need is some method that can detect the moment came back to origin tab after I go the to other tab.

Thx