Picker when button is tapped

I want to display picker when my button is tapped I have this view that a I re-use (view contains a textField and button)

I set the action to display the picker in the viewDidLoad

 InputViewController:UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {   var picker  = UIPickerView()override func viewDidLoad() {  super.viewDidLoad()  self.innerButton.addTarget(self, action: #selector(setPicker(sender:)), for: .touchUpInside)}@objc func setPicker(sender:UIButton){  let viewSizeWidth = UIScreen.main.bounds.size.width  picker = UIPickerView.init()  picker.delegate = self  picker.dataSource = self  picker.backgroundColor = UIColor.white  picker.setValue(UIColor.black, forKey: "textColor")  picker.autoresizingMask = .flexibleWidth  picker.contentMode = .center  picker.frame = CGRect.init(origin:  CGPoint.zero , size: CGSize(width: viewSizeWidth, height: 400))  self.view.addSubview(picker)}}

Actually this happens when I tapped my button:

(Button and textField disappears and picker looks squashed)My expected output is display picker with button and set selected raw in my textfield, what is missing in mi code ?