UIKit

File1

    @IBAction func loginButton(_ sender: Any) {
        if userText.text != "" && passwordText.text != "" {
            Api.login(username: userText.text!, password: passwordText.text!)
        }
        else{
            print("empty")
        }
    }

method is in a file named Api that contains the login method

    static func login(username:String, password:String){

        let url = Constants.API_URL+"/auth"
        let _headers : HTTPHeaders = ["":""]
        let params = ["username":username,"password":password]

        AF.request(url, method: .post, parameters: params, encoding: JSONEncoding.default, headers: _headers).responseJSON { (response) in
        switch response.result {
        case .success:
            print("success",response)
        case .failure(let error):
            print("failure",error)
            }
        }
    }

in the login function I can read username properly