StackView隐藏了导航栏/大标题

Question

如何将整个StackView设置在楼下，以使大标题可见？我是新手，对自动布局和stackViews的了解不足。 预先感谢！

import UIKit


class RegisterViewController: UIViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    
    let stackView = UIStackView()
    
    
    var profilePicture = UIButton()
    var profileIcon = UIImage()
    let usernameTextField = UITextField()
    let emailTextField = UITextField()
    let passswordTextField = UITextField()
    let signInButton = UIButton()
    
    
   
    

    override func viewDidLoad() {
        super.viewDidLoad()

设置导航栏和StackView

        navigationController?.navigationBar.prefersLargeTitles = true
        navigationItem.title = "Create an Account"
        view.backgroundColor = .white
        
        
        
        
        
        // SetUp StackView:
        stackView.translatesAutoresizingMaskIntoConstraints = false
        stackView.axis = .vertical
        stackView.alignment = .center
        stackView.distribution = .fillEqually
        stackView.spacing = 50
        view.addSubview(stackView)
       
        
        // SetUp Stack View Constraints:
       
       stackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor, constant: 20).isActive = true
       stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20).isActive = true
       stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20).isActive = true
               
        
        
        
    ```
...