Determines whether the calling thread has access to this DispatcherObject.
Assembly: WindowsBase (in WindowsBase.dll)
Any thread can check to see whether it has access to this DispatcherObject.
The difference between and VerifyAccess is that returns a Boolean that specifies whether the calling thread has access to this DispatcherObject and VerifyAccess throws an exception if the calling thread does not have access to the this DispatcherObject.
The following example uses to determine whether a thread has access to the thread that a Button was created on. The method on the Button is called to verify access to the thread. If the calling thread has access, the Button is updated by just accessing the members of the Button; otherwise, a delegate, which accepts a Button as an argument, is posted onto the Dispatcher of the Button.
' Uses the DispatcherObject.CheckAccess method to determine if ' the calling thread has access to the thread the UI object is on Private Sub TryToUpdateButtonCheckAccess(ByVal uiObject As Object) Dim theButton As Button = TryCast(uiObject, Button) If theButton IsNot Nothing Then ' Checking if this thread has access to the object If theButton.CheckAccess() Then ' This thread has access so it can update the UI thread UpdateButtonUI(theButton) Else ' This thread does not have access to the UI thread ' Pushing update method on the Dispatcher of the UI thread theButton.Dispatcher.BeginInvoke(DispatcherPriority.Normal, New UpdateUIDelegate(AddressOf UpdateButtonUI), theButton) End If End If End Sub
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.