Prompt Title: Add a overlaying button on a modal using UIKit

To overlay a button over a modal on iOS using UIKit without using SwiftUI or Storyboards, you can use the following approach:

1. Create the modal view controller and add the modal content as a subview. Here's an example of how to create a simple modal view controller:

lessCopy code
class ModalViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Add the modal content as a subview
        let modalContent = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        modalContent.backgroundColor = .white
        modalContent.layer.cornerRadius = 10
        
        view.addSubview(modalContent)
        
        // Center the modal content
        modalContent.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            modalContent.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            modalContent.centerYAnchor.constraint(equalTo: view.centerYAnchor),
            modalContent.widthAnchor.constraint(equalToConstant: 200),
            modalContent.heightAnchor.constraint(equalToConstant: 200)
        ])
    }
}

2. Add a button to the main view controller, and set its target to show the modal view controller:

lessCopy code
class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Add a button
        let button = UIButton(type: .system)
        button.setTitle("Show Modal", for: .normal)
        button.addTarget(self, action: #selector(showModal), for: .touchUpInside)
        
        view.addSubview(button)
        
        // Position the button
        button.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            button.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        ])
    }