PlayerPrefsStream

// Linked from http://unity3dhacks.blogspot.com/

/// <summary>
/// Enables stream IO on PlayerPrefs for Unity3D. Cheap replacement for FileStream on web player builds.
/// </summary>
public class PlayerPrefsStream : System.IO.Stream
{
    /// <summary>
    /// Creates a stream in PlayerPrefs using key "~". See overload if you want to use different key.
    /// </summary>
    public PlayerPrefsStream()
        : this("~")
    { 
    }

    /// <summary>
    /// Creates a stream in PlayerPrefs using a custom key.
    /// </summary>
    /// <param name="key">The location where to store the stream.</param>
    public PlayerPrefsStream(string key)
    {
        this.key = key;
        Load();
    }

    /// <summary>
    /// Reads all bytes from PlayerPrefs, using a key.
    /// </summary>
    /// <param name="key">The key in PlayerPrefs where the data is stored.</param>
    /// <returns>Array containing all bytes that could be retrieved.</returns>
    public static byte[] ReadAllBytes(string key)
    {
        return System.Convert.FromBase64String(UnityEngine.PlayerPrefs.GetString(key));
    }

    /// <summary>
    /// Writes all bytes to PlayerPrefs, using a key.
    /// </summary>
    /// <param name="key">The key in PlayerPrefs where the data is stored.</param>
    /// <param name="bytes">Array containing all bytes that should be written.</param>
    public static void WriteAllBytes(string key, byte[] bytes)
    {
        UnityEngine.PlayerPrefs.SetString(key, System.Convert.ToBase64String(bytes));
    }

    #region System.IO.Stream implementation

    /// <summary>
    /// See System.IO.MemoryStream.CanRead for more information.
    /// </summary>
    public override bool CanRead
    {
        get { return stream.CanRead; }
    }

    /// <summary>
    /// See System.IO.MemoryStream.CanSeek for more information.
    /// </summary>
    public override bool CanSeek
    {
        get { return stream.CanSeek; }
    }

    /// <summary>
    /// See System.IO.MemoryStream.CanWrite for more information.
    /// </summary>
    public override bool CanWrite
    {
        get { return stream.CanWrite; }
    }

    /// <summary>
    /// Writes the data to PlayerPrefs.
    /// </summary>
    public override void Flush()
    {
        stream.Flush();
        Save();
    }

    /// <summary>
    /// See System.IO.MemoryStream.Length for more information.
    /// </summary>
    public override long Length
    {
        get { return stream.Length; }
    }

    /// <summary>
    /// See System.IO.MemoryStream.Position for more information.
    /// </summary>
    public override long Position
    {
        get
        {
            return stream.Position;
        }
        set
        {
            stream.Position = value;
        }
    }

    /// <summary>
    /// See System.IO.MemoryStream.Read for more information.
    /// </summary>
    public override int Read(byte[] buffer, int offset, int count)
    {
        return stream.Read(buffer, offset, count);
    }

    /// <summary>
    /// See System.IO.MemoryStream.Seek for more information.
    /// </summary>
    public override long Seek(long offset, SeekOrigin origin)
    {
        return stream.Seek(offset, origin);
    }

    /// <summary>
    /// See System.IO.MemoryStream.SetLength for more information.
    /// </summary>
    public override void SetLength(long value)
    {
        stream.SetLength(value);
    }

    /// <summary>
    /// See System.IO.MemoryStream.Write for more information.
    /// </summary>
    public override void Write(byte[] buffer, int offset, int count)
    {
        stream.Write(buffer, offset, count);
    }

    #endregion

    /// <summary>
    /// Loads data from key.
    /// </summary>
    private void Load()
    {
        stream = new System.IO.MemoryStream();
        if (UnityEngine.PlayerPrefs.HasKey(key))
        {
            byte[] bytes = ReadAllBytes(key);
            stream.Write(bytes, 0, bytes.Length);
            stream.Position = 0;
        }
    }

    /// <summary>
    /// Saves data to key.
    /// </summary>
    private void Save()
    {
        byte[] bytes = stream.GetBuffer();
        WriteAllBytes(key, bytes);
    }

    /// <summary>
    /// Location in PlayerPrefs where data goes.
    /// </summary>
    private string key;

    /// <summary>
    /// Temporary stream to write data to.
    /// </summary>
    private MemoryStream stream;
}