WindowsRuntimeStorageExtensions Class

Reference

Definition

Namespace:: System.IO

Assembly:: System.Runtime.WindowsRuntime.dll

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Contains extension methods for the IStorageFile and IStorageFolder interfaces in the Windows Runtime when developing Windows Store apps.

public ref class WindowsRuntimeStorageExtensions abstract sealed

[System.Security.SecurityCritical]
public static class WindowsRuntimeStorageExtensions

[<System.Security.SecurityCritical>]
type WindowsRuntimeStorageExtensions = class

Public Module WindowsRuntimeStorageExtensions

Inheritance: Object
WindowsRuntimeStorageExtensions

Attributes: SecurityCriticalAttribute

Examples

The following example shows how to open a file in the application data as a Stream in a Windows Store app, and write to it by using an instance of the StreamWriter class. It then reads the contents for the file by using an instance of the StreamReader class.

using System;
using System.IO;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;

namespace ExampleApplication
{
    public sealed partial class BlankPage : Page
    {
        public BlankPage()
        {
            this.InitializeComponent();
        }

        private async void CreateButton_Click(object sender, RoutedEventArgs e)
        {
            using (StreamWriter writer =
                new StreamWriter(await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(
                "testfile.txt",  CreationCollisionOption.OpenIfExists)))
            {
                await writer.WriteLineAsync("new entry");
                await writer.WriteLineAsync(UserText.Text);
            }
        }

        private async void VerifyButton_Click(object sender, RoutedEventArgs e)
        {
            StorageFile openedFile = await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt");
            using (StreamReader reader = new StreamReader(await openedFile.OpenStreamForReadAsync()))
            {
                Results.Text = await reader.ReadToEndAsync();
            }
        }
    }
}

Imports System.IO
Imports Windows.Storage

NotInheritable Public Class BlankPage
    Inherits Page

    Private Async Sub CreateButton_Click(sender As Object, e As RoutedEventArgs)
        Using writer As StreamWriter =
               New StreamWriter(Await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(
               "testfile.txt", CreationCollisionOption.OpenIfExists))
            Await writer.WriteLineAsync("new entry")
            Await writer.WriteLineAsync(UserText.Text)
        End Using
    End Sub

    Private Async Sub VerifyButton_Click(sender As Object, e As RoutedEventArgs)
        Dim openedFile As StorageFile = Await ApplicationData.Current.LocalFolder.GetFileAsync("testfile.txt")
        Using reader As StreamReader = New StreamReader(Await openedFile.OpenStreamForReadAsync())
            Results.Text = Await reader.ReadToEndAsync()
        End Using
    End Sub
End Class

The next example shows the XAML code that is associated with the previous example.

<Page
    x:Class="ExampleApplication.BlankPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:ExampleApplication"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">

    <StackPanel Background="{StaticResource ApplicationPageBackgroundBrush}" VerticalAlignment="Center" HorizontalAlignment="Center">
        <TextBlock Text="Provide text to write to file:"></TextBlock>
        <TextBox Name="UserText" Width="400"></TextBox>
        <Button Name="CreateButton" Content="Create File" Click="CreateButton_Click"></Button>
        <Button Name="VerifyButton" Content="Verify Contents" Click="VerifyButton_Click"></Button>
        <TextBlock Name="Results"></TextBlock>
    </StackPanel>
</Page>

Remarks

These extension methods are available only when you develop Windows Store apps. The methods provide convenient ways of opening files for reading or writing in Windows Store apps. You do not create an instance of the WindowsRuntimeStorageExtensions class; instead, you use these methods from instances of the IStorageFile and IStorageFolder interfaces.

The WindowsRuntimeStorageExtensions class contains two methods that extend IStorageFile for reading or writing:

The WindowsRuntimeStorageExtensions class contains two methods that extend IStorageFolder for reading and writing:

Methods

OpenStreamForReadAsync(IStorageFile)	Retrieves a stream for reading from a specified file.
OpenStreamForReadAsync(IStorageFolder, String)	Retrieves a stream for reading from a file in the specified parent folder.
OpenStreamForWriteAsync(IStorageFile)	Retrieves a stream for writing to a specified file.
OpenStreamForWriteAsync(IStorageFolder, String, CreationCollisionOption)	Retrieves a stream for writing to a file in the specified parent folder.

Applies to

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