A navigator has a NavigationService that handles content navigation. WPF has two navigators: NavigationWindow and Frame. To process navigation requests and manage navigation lifetime, a navigator uses the WPF navigation service, which is implemented as the NavigationService class. Content that is hosted by a navigator can get a reference to the navigator's NavigationService by calling the GetNavigationService method.

GetNavigationService returns nullNothingnullptra null reference (Nothing in Visual Basic) when the dependencyObject:

• Is a NavigationWindow.

• Is a Frame that:

  1. Is hosted by another navigator.

  2. Has its JournalOwnership property set to UsesParentJournal.

• Is not part of content that is hosted by a navigator.

WPF offers two shortcuts for acquiring a reference to the NavigationService:

• The NavigationService that processed the navigation to a Page can be accessed from the Page itself by getting the value of its Page..::.NavigationService property.

• The NavigationService that is used by a Frame to process navigation can be accessed by getting the value of the NavigationService property.

The following example shows how a UserControl can retrieve a navigation service by calling GetNavigationService.

Private Sub getNavigationServiceButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
    ' Retrieve first navigation service up the content tree
    Dim svc As NavigationService = NavigationService.GetNavigationService(Me.getNavigationServiceButton)
    If svc IsNot Nothing Then
        ' Use navigation service


...


    End If
End Sub

void getNavigationServiceButton_Click(object sender, RoutedEventArgs e) {
    // Retrieve first navigation service up the content tree
    NavigationService svc = NavigationService.GetNavigationService(this.getNavigationServiceButton);
    if (svc != null)
    {
        // Use navigation service


...


    }
}

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference