UITextField не отвечает на нажатие в пользовательском интерфейсе, созданном программно

import UIKit

class TestController: UIViewController, UITextFieldDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .white
        initUI()
    }

    func initUI() {
        let scrollView = UIScrollView()
        scrollView.translatesAutoresizingMaskIntoConstraints = false
        scrollView.isUserInteractionEnabled = true
        view.addSubview(scrollView)

        let contentView = UIView()
        contentView.translatesAutoresizingMaskIntoConstraints = false
        contentView.isUserInteractionEnabled = true
        contentView.isMultipleTouchEnabled = true
        scrollView.addSubview(contentView)

        let titleText = UITextField(frame: CGRect.zero)
        titleText.translatesAutoresizingMaskIntoConstraints = false
        titleText.borderStyle = .roundedRect
        titleText.isEnabled = true
        titleText.isUserInteractionEnabled = true
        titleText.placeholder = "Constants.Messages.titlePlaceholder"
        titleText.isUserInteractionEnabled = true
        titleText.delegate = self
        contentView.addSubview(titleText)

        // scroll view
        NSLayoutConstraint.activate([
            scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 8.0),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -8.0),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8.0)
            ])
        // content view
        NSLayoutConstraint.activate([
            contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
            contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
            contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
            contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
            contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
            ])
        // title text field
        NSLayoutConstraint.activate([
            titleText.topAnchor.constraint(equalTo: contentView.topAnchor, constant: 20.0),
            titleText.leadingAnchor.constraint(equalTo: contentView.leadingAnchor, constant: 8.0),
            titleText.trailingAnchor.constraint(equalTo: contentView.trailingAnchor, constant: -8.0),
            titleText.bottomAnchor.constraint(equalTo: contentView.bottomAnchor, constant: 0)
            ])
    }
}

Попробуйте этот код, он будет работать для вас. Я протестировал ваш код и не использую принудительную распаковку при выполнении программных действий.

Проблема с вашим кодом заключается в том, что вы должны использовать нижнюю привязку при использовании UIScrollView, и вы помещаете «Текстовое поле заголовка в ScrollView» вместо того, чтобы вставлять ScrollView, вы должны привязываться к contentView.

func initUI() {

    let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height))
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    self.view.addSubview(scrollView)

    let contentView = UIView(frame: CGRect(x: 0, y: 0, width: scrollView.frame.size.width, height: scrollView.frame.size.height))
    contentView.backgroundColor = UIColor.red
    scrollView.addSubview(contentView)


    let titleText =  UITextField(frame: CGRect(x: 20, y: 100, width: 300, height: 40))
    titleText.placeholder = "Enter text here"
    titleText.font = UIFont.systemFont(ofSize: 15)
    titleText.borderStyle = UITextField.BorderStyle.roundedRect
    titleText.autocorrectionType = UITextAutocorrectionType.no
    titleText.keyboardType = UIKeyboardType.default
    titleText.returnKeyType = UIReturnKeyType.done
    titleText.clearButtonMode = UITextField.ViewMode.whileEditing
    titleText.contentVerticalAlignment = UIControl.ContentVerticalAlignment.center
    titleText.delegate = self
    contentView.addSubview(titleText)



    // scroll view
    NSLayoutConstraint.activate([
        scrollView.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
        scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 8.0),
        scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -8.0),
        scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -8.0)
        ])
    // content view
    NSLayoutConstraint.activate([
        contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
        contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
        contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
        contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
        contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
        ])

    // title text field
    NSLayoutConstraint.activate([
        titleText.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 20.0),
        titleText.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor, constant: 8.0),
        titleText.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor, constant: -8.0)
        ])
}