解密.net在iOS中加密的字符串

我在c#中做了一些AES加密，效果很好。代码:

public string EncryptStringAES(string plainText, string sharedSecret)
{
    if (string.IsNullOrEmpty(plainText))
        throw new ArgumentNullException("plainText");
    if (string.IsNullOrEmpty(sharedSecret))
        throw new ArgumentNullException("sharedSecret");
    string outStr = null;                       // Encrypted string to return
    RijndaelManaged aesAlg = null;              // RijndaelManaged object used to encrypt the data.
    try
    {
        _pkey = sharedSecret;
        // generate the key from the shared secret and the salt
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
        //_key = key.ToString();
        // Create a RijndaelManaged object
        aesAlg = new RijndaelManaged();
        aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
        _key = Encoding.ASCII.GetString(aesAlg.Key);
        // Create a decryptor to perform the stream transform.
        ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
        // Create the streams used for encryption.
        using (MemoryStream msEncrypt = new MemoryStream())
        {
            // prepend the IV
            msEncrypt.Write(BitConverter.GetBytes(aesAlg.IV.Length), 0, sizeof(int));
            msEncrypt.Write(aesAlg.IV, 0, aesAlg.IV.Length);
            using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
            {
                using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                {
                    //Write all data to the stream.
                    swEncrypt.Write(plainText);
                }
            }
            outStr = Convert.ToBase64String(msEncrypt.ToArray());
        }
    }
    finally
    {
        // Clear the RijndaelManaged object.
        if (aesAlg != null)
            aesAlg.Clear();
    }
    // Return the encrypted bytes from the memory stream.
    return outStr;
}
/// <summary>
/// Decrypt the given string.  Assumes the string was encrypted using 
/// EncryptStringAES(), using an identical sharedSecret.
/// </summary>
/// <param name="cipherText">The text to decrypt.</param>
/// <param name="sharedSecret">A password used to generate a key for decryption.</param>
public string DecryptStringAES(string cipherText, string sharedSecret)
{
    if (string.IsNullOrEmpty(cipherText))
        throw new ArgumentNullException("cipherText");
    if (string.IsNullOrEmpty(sharedSecret))
        throw new ArgumentNullException("sharedSecret");
    // Declare the RijndaelManaged object
    // used to decrypt the data.
    RijndaelManaged aesAlg = null;
    // Declare the string used to hold
    // the decrypted text.
    string plaintext = null;
    try
    {
        _pkey = sharedSecret;
        // generate the key from the shared secret and the salt
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(sharedSecret, _salt);
        //_key = key.ToString();
        // Create the streams used for decryption.                
        byte[] bytes = Convert.FromBase64String(cipherText);
        using (MemoryStream msDecrypt = new MemoryStream(bytes))
        {
            // Create a RijndaelManaged object
            // with the specified key and IV.
            aesAlg = new RijndaelManaged();
            aesAlg.Key = key.GetBytes(aesAlg.KeySize / 8);
            _key = Encoding.ASCII.GetString(aesAlg.Key);
            // Get the initialization vector from the encrypted stream
            aesAlg.IV = ReadByteArray(msDecrypt);
            // Create a decrytor to perform the stream transform.
            ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);
            using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
            {
                using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                    // Read the decrypted bytes from the decrypting stream
                    // and place them in a string.
                    plaintext = srDecrypt.ReadToEnd();
            }
        }
    }
    finally
    {
        // Clear the RijndaelManaged object.
        if (aesAlg != null)
            aesAlg.Clear();
    }
    return plaintext;
}

注意:我在这里加密了相当多的数据(大json字符串)

下一步将是在iOS上创造同样的奇迹，这里的问题是我是iOS的新手，我希望有人能给我指出正确的方向。

问题:

1. 我到目前为止未能找到iOS上如何使用秘密和盐密钥制作Rfc289密钥的示例
2. 我尝试了这个例子，这里的技巧是c#代码不与大字符串工作，它只与短字符串工作。

基本上我想要一些建议或其他一些方法，使rest api Web Service Application和iOS之间的安全通信。

谢谢你的帮助