通知所有订阅的观察者序列的结尾。
Namespace：System.Reactive.Subjects
装配： System.Reactive.dll) 中的 System.Reactive (
语法
'Declaration
Public Sub OnCompleted
'Usage
Dim instance As ReplaySubject
instance.OnCompleted()
public void OnCompleted()
public:
virtual void OnCompleted() sealed
abstract OnCompleted : unit -> unit
override OnCompleted : unit -> unit
public final function OnCompleted()