SecKey (PCKS1) to Base64 (PCKS8) from p12

Question

I have looked at other answers on StackOverflow and I didn't find what I was looking for (IOS11). I have a SecKey (privateKey) that when I print:

SecKeyRef algorithm id: 1, key type: RSAPrivateKey, version: 4, block size: 2048 bits, addr: 0x1d0223f60

I have tried to convert it to Data and from there to Base64

let password = "1234"
let p12data = NSData(contentsOfFile: urls[0].path)!
var importResult: CFArray? = nil
let err = SecPKCS12Import(p12data as NSData,[kSecImportExportPassphrase as String: password] as NSDictionary,&importResult )

//GET IDENTITY
let identityDictionaries = importResult as! [[String:Any]]
var privateKey: SecKey?
//GET SECKEY
SecIdentityCopyPrivateKey(identityDictionaries[0][kSecImportItemIdentity as String] as! SecIdentity, &privateKey);
print(privateKey)

//Return data in PCKS1
let dataPrivate = SecKeyCopyExternalRepresentation(privateKey!, nil)
let b64Key:Data = dataPrivate as! Data
print(b64Key.base64EncodedString(options: .lineLength64Characters))

Apple documentation says that SecKeyCopyExternalRepresentation return PCKS1 data (https://developer.apple.com/documentation/security/1643698-seckeycopyexternalrepresentation) but I need PCKS8.

The result is a base64 from PCKS1 but I have to send it to a JAVA server to be processed and expected format is base64 from PCKS8.

is there a way to convert from PCKS1 to PCKS8 and then to base64?

I have found this article: https://blog.wingsofhermes.org/?p=42 that more or less is what I want but its in objective-c and I have not been able to convert it to swift