AES encryption with GCM Mode using crypto swift

Code Block 
static func encryptsData(parameters: parameters?) -> (String, String) {
        // Convert Parameters in Json string
        var jsonStr = DefaultValues.empty
        do {
            if let str = String(data: try JSONSerialization.data(withJSONObject: parameters ?? [:], options: .prettyPrinted), encoding: .utf8) {
                jsonStr = str
            }
        } catch {
            debugPrint(error.localizedDescription)
        }
        // Get Secrete key, iv of 128 bits
        let iv = [UInt8](repeating: 0, count: 16)
        let randomStr = randomString(length: 16)
        let key: Array<UInt8> = Array(randomStr.utf8)
        // Encrypt Request Data with Secrete Key (AES)
        let aes =  try! AES(key: key, blockMode: CBC(iv: iv), padding: .pkcs5)
        let encrypted = try? aes.encrypt(Array(jsonStr.utf8))
        if let encryptedMsg = encrypted {
            let encryptedData =  Data(bytes: encryptedMsg, count: Int(encryptedMsg.count))
            let encryptedBase64 = encryptedData.base64EncodedString()
            //Encrypt Secrete Key using Server Public key (RSA)
            let keyData = Data(bytes: key, count: key.count)
            let encryptedSceKey = encryptSecKeyWithPublickKey(key: String(data: keyData, encoding: .utf8) ?? "")
            return (encryptedBase64, encryptedSceKey)
        }
        return (DefaultValues.empty, DefaultValues.empty)
    }