RSA Key Generating use Security, SecKeyCreateRandomKey

i want make RSA pair key to 512bit

i find SecKeyCreateRandomKey, CrytoKit, another open lib.. I decided to use Security

I have to give the server developer the string value of the rsa file I created I sent you an rsa string but server developer answered that the format was wrong I wonder what is wrong with my code. Or I want to be helped to generate an rsa key and chage type into a string

this is my code

first - make private key using SecKeyCreateRandomKey

func createPrivateKey()-> SecKey?{
     
    let privateKeyParams: [String: Any] = [
      kSecAttrIsPermanent as String: true,
      kSecAttrApplicationTag as String: tagName
    ]
     
    let parameters: [String: Any] = [
      kSecAttrKeyType as String: kSecAttrKeyTypeRSA,
      kSecAttrKeySizeInBits as String: 512,
      kSecPrivateKeyAttrs as String: privateKeyParams
    ]
     
    var error: Unmanaged<CFError>?
     
    guard let privateKey = SecKeyCreateRandomKey(parameters as CFDictionary, &error) else
    {
      NSLog("\tError generating keypair. %@", "\(error!.takeRetainedValue().localizedDescription)")
      return nil
    }
    return privateKey
  }

second - get public key using private key of Seckey

func getPublicKey(key: SecKey) -> SecKey?{
    return SecKeyCopyPublicKey(key)
  }

third - get public key Data using public key seckey

func getPublicData(key: SecKey) -> CFData?{
    return SecKeyCopyExternalRepresentation(key, nil)
  }

fouth - string of public key using public key of Data

  public func exportPublicKey(_ rawPublicKeyBytes: Data, base64EncodingOptions: Data.Base64EncodingOptions = []) -> String?
  {
   Log.debug("exportPublicKey", rawPublicKeyBytes.base64EncodedString(options: base64EncodingOptions))
    return rawPublicKeyBytes.base64EncodedString(options: base64EncodingOptions)
  }

last i send result of exportPublicKey() rsa string like this

MEgCQQDCmgOuSGbG/Mtq2NnHlBQU5rsGnNf17h4NZy+2lyrjKGgaVpD66QHmx2Na+/QQaamEhUgkFAkj0UlkMTRWGKO5AgMBBBE=

or

-----BEGIN PUBLIC KEY-----
MEgCQQDCmgOuSGbG/Mtq2NnHlBQU5rsGnNf17h4NZy+2lyrjKGgaVpD66QHmx2Na+/QQaamEhUgkFAkj0UlkMTRWGKO5AgMBBBE=
-----END PUBLIC KEY-----