NavigationHelper Class

NavigationHelper aids in navigation between pages. It provides commands used to navigate back and forward as well as registers for standard mouse and keyboard shortcuts used to go back and forward in Windows and the hardware back button in Windows Phone. In addition it integrates SuspensionManger to handle process lifetime management and state management when navigating between pages.

Inheritance Hierarchy

SystemObject
Windows.UI.XamlDependencyObject
foodez.CommonNavigationHelper

Namespace: foodez.Common
Assembly: foodez.WindowsPhone (in foodez.WindowsPhone.exe) Version: 1.0.0.0 (1.0.0.0)

Syntax

C++

Copy

public class NavigationHelper : DependencyObject

Public Class NavigationHelper
	Inherits DependencyObject

public ref class NavigationHelper : public DependencyObject

type NavigationHelper =  
    class
        inherit DependencyObject
    end

The NavigationHelper type exposes the following members.

Constructors

	Name	Description
	NavigationHelper	Initializes a new instance of the NavigationHelper class.

Top

Methods

	Name	Description
	CanGoBack	Virtual method used by the GoBackCommand property to determine if the Frame can go back.
	CanGoForward	Virtual method used by the GoForwardCommand property to determine if the Frame can go forward.
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	Equals	Determines whether the specified object is equal to the current object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
	GetAnimationBaseValue	Returns any base value established for a dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
	GetHashCode	Serves as the default hash function. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
	GoBack	Virtual method used by the GoBackCommand property to invoke the GoBack method.
	GoForward	Virtual method used by the GoForwardCommand property to invoke the GoForward method.
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	OnNavigatedFrom	Invoked when this page will no longer be displayed in a Frame. This method calls SaveState, where all page specific navigation and process lifetime management logic should be placed.
	OnNavigatedTo	Invoked when this page is about to be displayed in a Frame. This method calls LoadState, where all page specific navigation and process lifetime management logic should be placed.
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

Top

Properties

	Name	Description
	Dispatcher	Gets the CoreDispatcher that this object is associated with. (Inherited from DependencyObject.)
	GoBackCommand	RelayCommand used to bind to the back Button's Command property for navigating to the most recent item in back navigation history, if a Frame manages its own navigation history. The RelayCommand is set up to use the virtual method GoBack as the Execute Action and CanGoBack for CanExecute.
	GoForwardCommand	RelayCommand used for navigating to the most recent item in the forward navigation history, if a Frame manages its own navigation history. The RelayCommand is set up to use the virtual method GoForward as the Execute Action and CanGoForward for CanExecute.

Top

Events

	Name	Description
	LoadState	Register this event on the current page to populate the page with content passed during navigation as well as any saved state provided when recreating a page from a prior session.
	SaveState	Register this event on the current page to preserve state associated with the current page in case the application is suspended or the page is discarded from the navigaqtion cache.

Top

Examples

To make use of NavigationHelper, follow these two steps or start with a BasicPage or any other Page item template other than BlankPage. 1) Create an instance of the NavigationHelper somewhere such as in the constructor for the page and register a callback for the LoadState and SaveState events.

Copy

public MyPage()
{
    this.InitializeComponent();
    var navigationHelper = new NavigationHelper(this);
    this.navigationHelper.LoadState += navigationHelper_LoadState;
    this.navigationHelper.SaveState += navigationHelper_SaveState;
}

private async void navigationHelper_LoadState(object sender, LoadStateEventArgs e)
{ }
private async void navigationHelper_SaveState(object sender, LoadStateEventArgs e)
{ }

2) Register the page to call into the NavigationHelper whenever the page participates in navigation by overriding the OnNavigatedTo(NavigationEventArgs) and OnNavigatedFrom(NavigationEventArgs) events.

Copy

protected override void OnNavigatedTo(NavigationEventArgs e)
{
    navigationHelper.OnNavigatedTo(e);
}

protected override void OnNavigatedFrom(NavigationEventArgs e)
{
    navigationHelper.OnNavigatedFrom(e);
}

Reference

foodez.Common Namespace