[Q] Saving to a file and than appending to that file - Windows Phone 8 Apps and Games

I am trying to create a Windows Phone app which allows me to create a text file and save it to the documents folder than after append to that same file after. I only need to create one file. How can I accomplish this? I have already gotten to the point where I can save to the documents folder but than after I cant append to that file only replace it. This is what I have:
using SDKTemplate;
using System;
using System.Collections.Generic;
using Windows.ApplicationModel.Activation;
using Windows.Storage;
using Windows.Storage.Pickers;
using Windows.Storage.Provider;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;
namespace FilePicker
{
/// <summary>
/// Implement IFileSavePickerContinuable interface, in order that Continuation Manager can automatically
/// trigger the method to process returned file.
/// </summary>
public sealed partial class Scenario4 : Page, IFileSavePickerContinuable
{
MainPage rootPage = MainPage.Current;
public Scenario4()
{
this.InitializeComponent();
SaveFileButton.Click += new RoutedEventHandler(SaveFileButton_Click);
}
private void SaveFileButton_Click(object sender, RoutedEventArgs e)
{
// Clear previous returned file name, if it exists, between iterations of this scenario
OutputTextBlock.Text = "";
FileSavePicker savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.DocumentsLibrary;
// Dropdown of file types the user can save the file as
savePicker.FileTypeChoices.Add("Plain Text", new List<string>() { ".csv" });
// Default file name if the user does not type one in or select a file to replace
savePicker.SuggestedFileName = "Employee Info " + AliasTxt.Text;
savePicker.PickSaveFileAndContinue();
}
/// <summary>
/// Handle the returned file from file picker
/// This method is triggered by ContinuationManager based on ActivationKind
/// </summary>
/// <param name="args">File save picker continuation activation argment. It cantains the file user selected with file save picker </param>
public async void ContinueFileSavePicker(FileSavePickerContinuationEventArgs args)
{
string answer;
string header;
string date = DateTime.Now.ToString("M/d/yyyy");
string alias = AliasTxt.Text;
int newDoc = 0;
header = "Notes" + Environment.NewLine;
answer =NotesTxt.Text;
StorageFile file = args.File;
if (file != null)
{
// Prevent updates to the remote version of the file until we finish making changes and call CompleteUpdatesAsync.
CachedFileManager.DeferUpdates(file);
// write to file
//if (newDoc == 0)
//{
await FileIO.WriteTextAsync(file, header);
newDoc = 1;
//}
await FileIO.AppendTextAsync(file, answer);
// Let Windows know that we're finished changing the file so the other app can update the remote version of the file.
// Completing updates may require Windows to ask for user input.
FileUpdateStatus status = await CachedFileManager.CompleteUpdatesAsync(file);
if (status == FileUpdateStatus.Complete)
{
OutputTextBlock.Text = "File was saved.";
}
else
{
OutputTextBlock.Text = "File couldn't be saved.";
}
}
else
{
OutputTextBlock.Text = "Operation cancelled.";
}
}
private void SaveFileButton_Click_1(object sender, RoutedEventArgs e)
{
}
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
#if WINDOWS_PHONE_APP
/// <summary>
/// ContinuationManager is used to detect if the most recent activation was due
/// to a continuation such as the FileOpenPicker or WebAuthenticationBroker
/// </summary>
public class ContinuationManager
{
IContinuationActivatedEventArgs args = null;
bool handled = false;
Guid id = Guid.Empty;
/// <summary>
/// Sets the ContinuationArgs for this instance. Using default Frame of current Window
/// Should be called by the main activation handling code in App.xaml.cs
/// </summary>
/// <param name="args">The activation args</param>
internal void Continue(IContinuationActivatedEventArgs args)
{
Continue(args, Window.Current.Content as Frame);
}
/// <summary>
/// Sets the ContinuationArgs for this instance. Should be called by the main activation
/// handling code in App.xaml.cs
/// </summary>
/// <param name="args">The activation args</param>
/// <param name="rootFrame">The frame control that contains the current page</param>
internal void Continue(IContinuationActivatedEventArgs args, Frame rootFrame)
{
if (args == null)
throw new ArgumentNullException("args");
if (this.args != null && !handled)
throw new InvalidOperationException("Can't set args more than once");
this.args = args;
this.handled = false;
this.id = Guid.NewGuid();
if (rootFrame == null)
return;
switch (args.Kind)
{
case ActivationKind.PickFileContinuation:
var fileOpenPickerPage = rootFrame.Content as IFileOpenPickerContinuable;
if (fileOpenPickerPage != null)
{
fileOpenPickerPage.ContinueFileOpenPicker(args as FileOpenPickerContinuationEventArgs);
}
break;
case ActivationKind.PickSaveFileContinuation:
var fileSavePickerPage = rootFrame.Content as IFileSavePickerContinuable;
if (fileSavePickerPage != null)
{
fileSavePickerPage.ContinueFileSavePicker(args as FileSavePickerContinuationEventArgs);
}
break;
case ActivationKind.PickFolderContinuation:
var folderPickerPage = rootFrame.Content as IFolderPickerContinuable;
if (folderPickerPage != null)
{
folderPickerPage.ContinueFolderPicker(args as FolderPickerContinuationEventArgs);
}
break;
case ActivationKind.WebAuthenticationBrokerContinuation:
var wabPage = rootFrame.Content as IWebAuthenticationContinuable;
if (wabPage != null)
{
wabPage.ContinueWebAuthentication(args as WebAuthenticationBrokerContinuationEventArgs);
}
break;
}
}
/// <summary>
/// Marks the contination data as 'stale', meaning that it is probably no longer of
/// any use. Called when the app is suspended (to ensure future activations don't appear
/// to be for the same continuation) and whenever the continuation data is retrieved
/// (so that it isn't retrieved on subsequent navigations)
/// </summary>
internal void MarkAsStale()
{
this.handled = true;
}
/// <summary>
/// Retrieves the continuation args, if they have not already been retrieved, and
/// prevents further retrieval via this property (to avoid accidentla double-usage)
/// </summary>
public IContinuationActivatedEventArgs ContinuationArgs
{
get
{
if (handled)
return null;
MarkAsStale();
return args;
}
}
/// <summary>
/// Unique identifier for this particular continuation. Most useful for components that
/// retrieve the continuation data via <see cref="GetContinuationArgs"/> and need
/// to perform their own replay check
/// </summary>
public Guid Id { get { return id; } }
/// <summary>
/// Retrieves the continuation args, optionally retrieving them even if they have already
/// been retrieved
/// </summary>
/// <param name="includeStaleArgs">Set to true to return args even if they have previously been returned</param>
/// <returns>The continuation args, or null if there aren't any</returns>
public IContinuationActivatedEventArgs GetContinuationArgs(bool includeStaleArgs)
{
if (!includeStaleArgs && handled)
return null;
MarkAsStale();
return args;
}
}
/// <summary>
/// Implement this interface if your page invokes the file open picker
/// API.
/// </summary>
interface IFileOpenPickerContinuable
{
/// <summary>
/// This method is invoked when the file open picker returns picked
/// files
/// </summary>
/// <param name="args">Activated event args object that contains returned files from file open picker</param>
void ContinueFileOpenPicker(FileOpenPickerContinuationEventArgs args);
}
/// <summary>
/// Implement this interface if your page invokes the file save picker
/// API
/// </summary>
interface IFileSavePickerContinuable
{
/// <summary>
/// This method is invoked when the file save picker returns saved
/// files
/// </summary>
/// <param name="args">Activated event args object that contains returned file from file save picker</param>
void ContinueFileSavePicker(FileSavePickerContinuationEventArgs args);
}
/// <summary>
/// Implement this interface if your page invokes the folder picker API
/// </summary>
interface IFolderPickerContinuable
{
/// <summary>
/// This method is invoked when the folder picker returns the picked
/// folder
/// </summary>
/// <param name="args">Activated event args object that contains returned folder from folder picker</param>
void ContinueFolderPicker(FolderPickerContinuationEventArgs args);
}
/// <summary>
/// Implement this interface if your page invokes the web authentication
/// broker
/// </summary>
interface IWebAuthenticationContinuable
{
/// <summary>
/// This method is invoked when the web authentication broker returns
/// with the authentication result
/// </summary>
/// <param name="args">Activated event args object that contains returned authentication token</param>
void ContinueWebAuthentication(WebAuthenticationBrokerContinuationEventArgs args);
}
#endif

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It would be interesting check it...