UILabel updates automatically when UITextField is updated in UIKit (surprisingly hard to do).

ViewController.swift

import UIKit

class HomeViewController: UIViewController, UITextFieldDelegate {

    let style = UITraitCollection().userInterfaceStyle
    
    var textField: UITextField = {
        let textField = UITextField()
        textField.translatesAutoresizingMaskIntoConstraints = false
        textField.backgroundColor = .systemBackground
        textField.placeholder = "Enter some text here"
        textField.adjustsFontForContentSizeCategory = true
        return textField }()
    var label: UILabel = {
        let label = UILabel()
        label.translatesAutoresizingMaskIntoConstraints = false
        label.backgroundColor = .systemBackground
        label.text = "This is a label."
        label.adjustsFontForContentSizeCategory = true
        return label }()

    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = .secondarySystemBackground
        
        textField.delegate = self
        
        view.addSubview(textField)
        view.addSubview(label)
        addConstraints()
        
    }

    
    func addConstraints() {
        
        textField.topAnchor.constraint(
            equalTo: self.view.safeAreaLayoutGuide.topAnchor).isActive = true
        textField.leadingAnchor.constraint(
            equalTo: self.view.safeAreaLayoutGuide.leadingAnchor, constant: self.view.bounds.width / 10).isActive = true
        textField.trailingAnchor.constraint(
            equalTo: self.view.safeAreaLayoutGuide.trailingAnchor, constant: -(self.view.bounds.width / 10)).isActive = true
        textField.textColor = {
            if self.traitCollection.userInterfaceStyle.rawValue == 2 { return .white }
            else { return .black } }()
        
        label.topAnchor.constraint(
            equalTo: textField.bottomAnchor, constant: 10).isActive = true
        label.leadingAnchor.constraint(
            equalTo: textField.leadingAnchor).isActive = true
        label.trailingAnchor.constraint(
            equalTo: textField.trailingAnchor).isActive = true
        label.textColor = {
            if self.traitCollection.userInterfaceStyle.rawValue == 2 { return .white }
            else { return .black } }()
        
    }
    
    
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let updatedText = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
        if string == "" && range.length == 1 && label.text == label.text && label.text != updatedText {
            label.text = updatedText
        } else {
            label.text = textField.text
        }
        return true
    }
    
    func textFieldDidBeginEditing(_ textField: UITextField) {
        if label.text != "" {
            label.text = " "
        }
    }

}