Assembly: System.Web (in system.web.dll)
Return ValueThe object that contains the changes to the view state of the StateManagedCollection and the items it contains. If no view state is associated with the collection and its elements, 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. For more information, see ASP.NET Web Server Controls.
When view state is saved, this string object is returned to the client as a variable that is stored in an HTML hidden element (<input type="hidden">). When you author custom server controls, you can improve efficiency by overriding this method and modifying your server control's ViewState property. For more information, see ASP.NET Web Server Controls andASP.NET State Management.