Nice little extension methods when using the Live 5.6 SDK to interact with OneDrive in a Windows Phone project. I needed a way to upload/download an encrypted text file from a user's OneDrive account for data backup for my app, #PassSafe. Feel free to let me know if I missed anything or if I can help you integrate this into your app!

OneDriveExtensions

using System;
using System.Collections.Generic;
using System.IO;
using System.IO.IsolatedStorage;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Microsoft.Live;

// https://stackoverflow.com/questions/23715282/onedrive-upload-download-to-specified-directory
namespace OneDriveEx.Helpers
{
    public static class OneDriveHelper
    {
        /// <summary>
        /// Creates or gets the directory ID from OneDrive.  Provided by colleague Ertay Shashko.
        /// </summary>
        /// <param name="client">The current Live Connect session object.</param>
        /// <param name="folderName">Folder name to create or get.</param>
        /// <param name="parentFolder">The parent folder to query.</param>
        /// <returns>Directory ID from OneDrive.</returns>
        public async static Task<string> CreateOrGetDirectoryAsync(this LiveConnectClient client, string folderName, string parentFolder)
        {
            string folderId = null;

            // Retrieves all the directories.
            var queryFolder = parentFolder + "/files?filter=folders,albums";
            var opResult = await client.GetAsync(queryFolder);
            dynamic result = opResult.Result;

            foreach (dynamic folder in result.data)
            {
                // Checks if current folder has the passed name.
                if (folder.name.ToLowerInvariant() == folderName.ToLowerInvariant())
                {
                    folderId = folder.id;
                    break;
                }
            }

            if (folderId == null)
            {
                // Directory hasn't been found, so creates it using the PostAsync method.
                var folderData = new Dictionary<string, object>();
                folderData.Add("name", folderName);
                opResult = await client.PostAsync(parentFolder, folderData);
                result = opResult.Result;

                // Retrieves the id of the created folder.
                folderId = result.id;
            }

            return folderId;
        }

        /// <summary>
        /// Uploads a text file to the specified directory on a user's OneDrive account.
        /// </summary>
        /// <param name="client">The current Live Connect session object.</param>
        /// <param name="directory">Directory name to upload the file to.  If the directory does not exist, it will be created.</param>
        /// <param name="fileName">Name of the text file to write.</param>
        /// <param name="textToWrite">Text to write into the text file.</param>
        /// <returns />
        public async static Task UploadFileAsync(this LiveConnectClient client, string directory, string fileName, string textToWrite)
        {
            using (var isoStoreFile = IsolatedStorageFile.GetUserStoreForApplication())
            {
                // Creates the text file in Isolated Storage
                using (var writeFile = new StreamWriter(new IsolatedStorageFileStream(fileName, FileMode.Create, FileAccess.Write, isoStoreFile)))
                {
                    await writeFile.WriteLineAsync(textToWrite);
                }

                // Uses the iso file created above to upload it to OneDrive
                using (var isoStoreFileStream = isoStoreFile.OpenFile(fileName, FileMode.Open, FileAccess.Read))
                {
                    string oneDriveDirectory = await OneDriveHelper.CreateOrGetDirectoryAsync(client, directory, "me/skydrive");
                   
                    var result = await client.UploadAsync(oneDriveDirectory, fileName,
                                                  isoStoreFileStream, OverwriteOption.Overwrite);
                }
            }
        }

        /// <summary>
        /// Downloads a text file from OneDrive, reads it, and returns the text.
        /// </summary>
        /// <param name="client">The current Live Connect session object.</param>
        /// <param name="directory">Directory name to download the file from.</param>
        /// <param name="fileName">Name of the text file to read.</param>
        /// <returns>Text read from the specified file.</returns>
        public async static Task<string> DownloadFileAsync(this LiveConnectClient client, string directory, string fileName)
        {
            // Get the directory ID we want
            string oneDriveDirectoryId = await OneDriveHelper.CreateOrGetDirectoryAsync(client, directory, "me/skydrive");
            var result = await client.DownloadAsync(oneDriveDirectoryId);

            // Get the files inside of the directory ID we specified above
            var operation = await client.GetAsync(oneDriveDirectoryId + "/files");

            // Look at the data return list
            var items = operation.Result["data"] as List<object>;
            
            // We will store the OneDrive file ID in the var "id"
            string id = string.Empty;

            // Search for the file name we want to read, as specified by the overload "fileName"
            foreach (object item in items)
            {
                var file = item as IDictionary<string, object>;
                if (file["name"].ToString() == fileName)
                {
                    // If we find the file, assign the OneDrive ID to the id var
                    id = file["id"].ToString();
                    break;
                }
            }

            // If the file name was not found, throw ex
            if (string.IsNullOrEmpty(id))
                throw new FileNotFoundException("Could not locate the file on the OneDrive account.");

            // Download the contents of the file
            var downloadResult = await client.DownloadAsync(string.Format("{0}/content", id));

            // Read the file and return the text
            using (var reader = new StreamReader(downloadResult.Stream, Encoding.UTF8))
            {           
                string text = await reader.ReadToEndAsync();
                return text;
            }
        }
    }
}

ViewCodeBehind

//Shows usage of OneDriveExtensions

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using Microsoft.Phone.Controls;
using Microsoft.Phone.Shell;
using Microsoft.Live;

namespace OneDriveEx.Views
{
    public partial class OneDriveView : PhoneApplicationPage
    {
        private LiveConnectClient _client;

        public OneDriveView()
        {
            InitializeComponent();
        }

        private void SignInButton_SessionChanged(object sender, Microsoft.Live.Controls.LiveConnectSessionChangedEventArgs e)
        {
            if (e != null && e.Status == LiveConnectSessionStatus.Connected)
            {
                _client = new LiveConnectClient(e.Session);
            }
            else
            {
                _client = null;
            }
        }

        private async void ApplicationBarBackup_Click(object sender, EventArgs e)
        {
            try
            {
                await Helpers.OneDriveHelper.UploadFileAsync(_client, "Example", "backup.txt", "Super awesome test!!!");
                MessageBox.Show("Data backup completed successfully!", "Hooray!", MessageBoxButton.OK);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Uh-oh!", MessageBoxButton.OK);
            }
        }

        private async void ApplicationBarRestore_Click(object sender, EventArgs e)
        {

            try
            {
                var result = await Helpers.OneDriveHelper.DownloadFileAsync(_client, "Example", "backup.txt");
                if (result == "Super awesome test!!!")
                    MessageBox.Show("Data restore completed successfully!", "Hooray!", MessageBoxButton.OK);
                else
                    MessageBox.Show("That didn't work....", "Oops!", MessageBoxButton.OK);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Uh-oh!", MessageBoxButton.OK);
            }
        }
    }
}