unity3d - How do you reference UI Event System from script? -

i tried creating public variable , referencing eventsystem object inspector of gameobject script attached to, whenever try access variable eventsystems,

i nullreference exception: object reference not set instance of object.

i tried finding gameobject.find() apparently can't cast gameobject eventsystem.eventsystem in-built cast.

i'm not sure do. want access

eventsystem.currentselectedgameobject.name

to find out ui object in canvas selected.

here want, see documentation here.

eventsystem.current