AppDelegate.m

- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
    NSLog(@"My token is: %@", deviceToken);
}

- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error {
    NSLog(@"Failed to get token, error: %@", error);
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
    NSLog(@"Received remote notification: %@", userInfo);
}

push_test.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Net.Sockets;
using System.Security.Cryptography;
using System.Security.Authentication;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;

namespace Tinkering
{
    class Program
    {
        // Get the APNS cert
        private static X509Certificate getServerCert()
        {
            // Open the cert store on the Local Machine
            X509Store store = new X509Store(StoreLocation.LocalMachine);

            if (store != null)
            {
                // Store exists, so open it and search through the certs for the Apple cert

                store.Open(OpenFlags.ReadOnly);
                X509Certificate2Collection certs = store.Certificates;

                if (certs.Count > 0)
                {
                    int i;
                    for (i = 0; i < certs.Count; i++)
                    {
                        X509Certificate2 cert = certs[i];

                        if (cert.FriendlyName.Contains("Apple Development IOS Push Services"))
                        {
                            // Cert found, so return it
                            return certs[i];
                        }
                    }
                }
            }

            return null;
        }

        private static Stream s_PushConnection;

        private static Stream PushConnection
        {
            get
            {
                if (s_PushConnection == null || !s_PushConnection.CanWrite)
                {
                    TcpClient client = new TcpClient("gateway.sandbox.push.apple.com", 2195);
                    SslStream ssl = new SslStream(client.GetStream(), false, null);
                    try
                    {
                        X509Certificate cert = getServerCert();
                        ssl.AuthenticateAsClient("gateway.sandbox.push.apple.com",
                            new X509CertificateCollection(new X509Certificate[] { cert }),
                            System.Security.Authentication.SslProtocols.Default,
                            true);
                    }
                    catch (AuthenticationException e)
                    {
                        client.Close();
                        ssl = null;
                        // need to log this
                        throw e;
                    }

                    s_PushConnection = ssl;
                }

                return s_PushConnection;
            }
        }

        private static byte[] HexStringToByteArray(string hex)
        {
            if ((hex.Length & 1) == 1)
                throw new Exception("The binary key cannot have an odd number of digits");

            byte[] arr = new byte[hex.Length >> 1];

            for (int i = 0; i < hex.Length; i += 2)
            {
                arr[i >> 1] = (byte)((GetHexVal(hex[i]) << 4) + (GetHexVal(hex[i + 1])));
            }

            return arr;
        }

        private static int GetHexVal(char hex)
        {
            int val = (int)hex;
            return val - (val < 58 ? 48 : (val < 97 ? 55 : 87));
        }


        static void Main(string[] args)
        {
            Guid envId = new Guid();
            string payload = String.Format("{{'aps':{{'alert':'This is a push notification'}},'envId':'{0}'}}", envId);

            BinaryWriter bw = new BinaryWriter(PushConnection);
            bw.Write((byte)0);

            //bw.Write((byte)1);
            //// identifier
            //bw.Write((uint)0xADADADAD);

            //uint expiry = (uint)(DateTime.Now - new DateTime(1970, 1, 1)).TotalSeconds + 86400;
            //bw.Write((byte)(expiry >> 24));
            //bw.Write((byte)(expiry >> 16));
            //bw.Write((byte)(expiry >> 8));
            //bw.Write((byte)expiry);

            byte[] DeviceId = HexStringToByteArray("dc1a93735d2b6a953a2f98ac886b8eee38a1c9498387565ccca5cc944c73a7e6");
            bw.Write((byte)(DeviceId.Length >> 8));
            bw.Write((byte)DeviceId.Length);
            bw.Write(DeviceId);

            bw.Write((byte)(payload.Length >> 8));
            bw.Write((byte)payload.Length);
            bw.Write(payload.ToCharArray(), 0, payload.Length);

            bw.Flush();
            //int i;
            //while ((i = PushConnection.ReadByte()) != -1)
            //    Console.WriteLine(i);
        }
    }
}

Xcode debugger log

My token is: <dc1a9373 5d2b6a95 3a2f98ac 886b8eee 38a1c949 8387565c cca5cc94 4c73a7e6>