Dynamically add nested stackviews to existing stackview after runtime - swift3

Question

Swift Newbie here, trying to learn the code. I have a javascript background though. I've designed a simple interface using nested stackviews in the storyboard:
The hierarchy is
Vertical Stack
-Horizontal Stack
-Vertical Stack
Label
Textfield
-Vertical Stack
Label
TextField
I've basically set up a table like display, that i want to replicate everytime a user clicks the "Add Member button" It needs to duplicate what's there and add it top stack. Add a New horizontal stack composed of two vertical stacks with the label and text fields.
When I press the button nothing happens. No errors either. I used a print to confirm the button event is firing.
here is the controller code:
class createCrewController: UIViewController{
//MARK: Properties
var memberList:UIStackView!
override func viewDidLoad() {
super.viewDidLoad()
memberList = view.viewWithTag(1) as! UIStackView!;
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
var rowArray = [UIStackView]()
//MARK: Actions
#IBAction func addMemberBTN(_ sender: UIButton) {
//Create name and TextField
let nameLabel = UILabel();
nameLabel.text = "Name";
let nameTextField = UITextField();
nameTextField.placeholder = "Enter Name";
let phoneLabel = UILabel();
phoneLabel.text = "Name";
let phoneTextField = UITextField();
phoneTextField.placeholder = "Enter Phone";
//Insert them into vertical Stack
let nameRow = UIStackView(arrangedSubviews: [nameLabel,nameTextField]);
nameRow.axis = .vertical;
let phoneRow = UIStackView(arrangedSubviews: [phoneLabel,phoneTextField]);
phoneRow.axis = .vertical;
let columnView = UIStackView(arrangedSubviews:[nameRow,phoneRow]);
columnView.axis = .horizontal;
self.memberList.addSubview(columnView);
}