Assembly: System.Web (in system.web.dll)
Return ValueThe Object that contains the changes to the Parameter view state. If there is no view state associated with the object, this method returns a null reference (Nothing in Visual Basic).
This method is used primarily by control developers.
View state is the accumulation of the values of a server control's properties. These values are automatically placed in the server control's ViewState property, which is an instance of the StateBag class. This property's value is then persisted to a string object after the save state stage of the server control life cycle.
When view state is saved, this string object is returned to the client as a variable that is stored in an HTML hidden element. When you author custom server controls, you can improve efficiency by overriding this method and modifying your server control's ViewState property.