AndroidExtensions.cs

using System;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

using Android.OS;
using Android.App;
using Android.Content;

public static class AndroidExtensions {
  static BinaryFormatter binaryFormatter;

	public static void PutObject (this Bundle bundle, string key, object val)
	{
		if (binaryFormatter == null)
			binaryFormatter = new BinaryFormatter ();

		using (var stream = new MemoryStream ()) {
			binaryFormatter.Serialize (stream, val);
			bundle.PutByteArray (key, stream.ToArray ());
		}
	}

	public static object GetObject (this Bundle bundle, string key)
	{
		if (binaryFormatter == null)
			binaryFormatter = new BinaryFormatter ();

		var array = bundle.GetByteArray (key);
		if (array == null)
			return null;

		using (var stream = new MemoryStream (array, false))
			return binaryFormatter.Deserialize (stream);
	}
}