The Application class in the Windows Phone Project performs the start-up activities of the windows phone app. The Windows Phone 8 SDK by default creates the App.xaml file which inherits from Application class. This file is created when the project is created.

The App.xaml can be used to store application level resources, styles etc. whereas the App.xaml.cs file is the code behind file where the application events can be handled.

App.xaml

<Application

x:Class="AbundantCodeWP8.App"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"

xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone">

<!--Application Resources-->

<Application.Resources>

<local:LocalizedStrings xmlns:local="clr-namespace:AbundantCodeWP8" x:Key="LocalizedStrings"/>

</Application.Resources>

<Application.ApplicationLifetimeObjects>

<!--Required object that handles lifetime events for the application-->

<shell:PhoneApplicationService

Launching="Application_Launching" Closing="Application_Closing"

Activated="Application_Activated" Deactivated="Application_Deactivated"/>

</Application.ApplicationLifetimeObjects>

</Application>

App.xaml.cs

using System;

using System.Diagnostics;

using System.Resources;

using System.Windows;

using System.Windows.Markup;

using System.Windows.Navigation;

using Microsoft.Phone.Controls;

using Microsoft.Phone.Shell;

using AbundantCodeWP8.Resources;

namespace AbundantCodeWP8

{

public partial class App : Application

{

/// <summary>

/// Provides easy access to the root frame of the Phone Application.

/// </summary>

/// <returns>The root frame of the Phone Application.</returns>

public static PhoneApplicationFrame RootFrame { get; private set; }

/// <summary>

/// Constructor for the Application object.

/// </summary>

public App()

{

// Global handler for uncaught exceptions.

UnhandledException += Application_UnhandledException;

// Standard XAML initialization

InitializeComponent();

// Phone-specific initialization

InitializePhoneApplication();

// Language display initialization

InitializeLanguage();

// Show graphics profiling information while debugging.

if (Debugger.IsAttached)

{

// Display the current frame rate counters.

Application.Current.Host.Settings.EnableFrameRateCounter = true;

// Show the areas of the app that are being redrawn in each frame.

//Application.Current.Host.Settings.EnableRedrawRegions = true;

// Enable non-production analysis visualization mode,

// which shows areas of a page that are handed off to GPU with a colored overlay.

//Application.Current.Host.Settings.EnableCacheVisualization = true;

// Prevent the screen from turning off while under the debugger by disabling

// the application's idle detection.

// Caution:- Use this under debug mode only. Application that disables user idle detection will continue to run

// and consume battery power when the user is not using the phone.

PhoneApplicationService.Current.UserIdleDetectionMode = IdleDetectionMode.Disabled;

}

}

// Code to execute when the application is launching (eg, from Start)

// This code will not execute when the application is reactivated

private void Application_Launching(object sender, LaunchingEventArgs e)

{

}

// Code to execute when the application is activated (brought to foreground)

// This code will not execute when the application is first launched

private void Application_Activated(object sender, ActivatedEventArgs e)

{

}

// Code to execute when the application is deactivated (sent to background)

// This code will not execute when the application is closing

private void Application_Deactivated(object sender, DeactivatedEventArgs e)

{

}

// Code to execute when the application is closing (eg, user hit Back)

// This code will not execute when the application is deactivated

private void Application_Closing(object sender, ClosingEventArgs e)

{

}

// Code to execute if a navigation fails

private void RootFrame_NavigationFailed(object sender, NavigationFailedEventArgs e)

{

if (Debugger.IsAttached)

{

// A navigation has failed; break into the debugger

Debugger.Break();

}

}

// Code to execute on Unhandled Exceptions

private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)

{

if (Debugger.IsAttached)

{

// An unhandled exception has occurred; break into the debugger

Debugger.Break();

}

}

#region Phone application initialization

// Avoid double-initialization

private bool phoneApplicationInitialized = false;

// Do not add any additional code to this method

private void InitializePhoneApplication()

{

if (phoneApplicationInitialized)

return;

// Create the frame but don't set it as RootVisual yet; this allows the splash

// screen to remain active until the application is ready to render.

RootFrame = new PhoneApplicationFrame();

RootFrame.Navigated += CompleteInitializePhoneApplication;

// Handle navigation failures

RootFrame.NavigationFailed += RootFrame_NavigationFailed;

// Handle reset requests for clearing the backstack

RootFrame.Navigated += CheckForResetNavigation;

// Ensure we don't initialize again

phoneApplicationInitialized = true;

}

// Do not add any additional code to this method

private void CompleteInitializePhoneApplication(object sender, NavigationEventArgs e)

{

// Set the root visual to allow the application to render

if (RootVisual != RootFrame)

RootVisual = RootFrame;

// Remove this handler since it is no longer needed

RootFrame.Navigated -= CompleteInitializePhoneApplication;

}

private void CheckForResetNavigation(object sender, NavigationEventArgs e)

{

// If the app has received a 'reset' navigation, then we need to check

// on the next navigation to see if the page stack should be reset

if (e.NavigationMode == NavigationMode.Reset)

RootFrame.Navigated += ClearBackStackAfterReset;

}

private void ClearBackStackAfterReset(object sender, NavigationEventArgs e)

{

// Unregister the event so it doesn't get called again

RootFrame.Navigated -= ClearBackStackAfterReset;

// Only clear the stack for 'new' (forward) and 'refresh' navigations

if (e.NavigationMode != NavigationMode.New && e.NavigationMode != NavigationMode.Refresh)

return;

// For UI consistency, clear the entire page stack

while (RootFrame.RemoveBackEntry() != null)

{

; // do nothing

}

}

#endregion

// Initialize the app's font and flow direction as defined in its localized resource strings.

//

// To ensure that the font of your application is aligned with its supported languages and that the

// FlowDirection for each of those languages follows its traditional direction, ResourceLanguage

// and ResourceFlowDirection should be initialized in each resx file to match these values with that

// file's culture. For example:

//

// AppResources.es-ES.resx

// ResourceLanguage's value should be "es-ES"

// ResourceFlowDirection's value should be "LeftToRight"

//

// AppResources.ar-SA.resx

// ResourceLanguage's value should be "ar-SA"

// ResourceFlowDirection's value should be "RightToLeft"

//

// For more info on localizing Windows Phone apps see http://go.microsoft.com/fwlink/?LinkId=262072.

//

private void InitializeLanguage()

{

try

{

// Set the font to match the display language defined by the

// ResourceLanguage resource string for each supported language.

//

// Fall back to the font of the neutral language if the Display

// language of the phone is not supported.

//

// If a compiler error is hit then ResourceLanguage is missing from

// the resource file.

RootFrame.Language = XmlLanguage.GetLanguage(AppResources.ResourceLanguage);

// Set the FlowDirection of all elements under the root frame based

// on the ResourceFlowDirection resource string for each

// supported language.

//

// If a compiler error is hit then ResourceFlowDirection is missing from

// the resource file.

FlowDirection flow = (FlowDirection)Enum.Parse(typeof(FlowDirection), AppResources.ResourceFlowDirection);

RootFrame.FlowDirection = flow;

}

catch

{

// If an exception is caught here it is most likely due to either

// ResourceLangauge not being correctly set to a supported language

// code or ResourceFlowDirection is set to a value other than LeftToRight

// or RightToLeft.

if (Debugger.IsAttached)

{

Debugger.Break();

}

throw;

}

}

}

}

Application Class in Windows Phone 8 Project

App.xaml

App.xaml.cs

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App.xaml

App.xaml.cs

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