(Swift 3,4,5...) AES Encryption ECB Mode with PKCS7 Padding

Duplicates the following C# code:

public static byte[] DecryptBySymmetricKey(string encryptedText, byte[] key)
  {
     string keyAsBase64 = Convert.ToBase64String(key);

     byte[] dataToDecrypt = Convert.FromBase64String(encryptedText);
     var keyBytes = key;
     AesManaged tdes = new AesManaged();
     tdes.KeySize = 256;
     tdes.BlockSize = 128;
     tdes.Key = keyBytes;
     tdes.Mode = CipherMode.ECB;
     tdes.Padding = PaddingMode.PKCS7;
     ICryptoTransform decrypt__1 = tdes.CreateDecryptor();
     byte[] deCipher = decrypt__1.TransformFinalBlock(dataToDecrypt, 0, dataToDecrypt.Length);
     tdes.Clear();
     string EK_result = Convert.ToBase64String(deCipher);
     return EK_result;
}

Chilkat Downloads for the Swift Programming Language MAC OS X (Cocoa) Objective-C/Swift Libs iOS Objective-C/Swift Libs

func chilkatTest() {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    let crypt = CkoCrypt2()!

    // In the C# code above that is to be duplicated here, use the base64 encoded key.
    var keyAsBase64: String? = "..."
    var encryptedBytesAsBase64: String? = "...."

    crypt.keyLength = 256
    crypt.cryptAlgorithm = "AES"
    crypt.cipherMode = "ecb"
    crypt.paddingScheme = 0
    crypt.setEncodedKey(keyAsBase64, encoding: "base64")

    crypt.encodingMode = "base64"

    // Pass the base64 representation of the encrypted data.
    // (The EncodingMode indicates you are passing base64.)
    var EK_result: String? = crypt.decryptStringENC(encryptedBytesAsBase64)

    print("\(EK_result!)")

}