Example page showing how to set auto layout to arrange a username field, password field, login button and forgot credential buttons in swift programmatically.

To set up auto layout for a username field, password field, login button, and forgot credential button programmatically in Swift, you can use the NSLayoutConstraint class to define the relationships between these UI elements. Here’s an example of how you can do this:

import UIKit

class YourViewController: UIViewController {

    // Create UI elements
    let usernameField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Username"
        textField.borderStyle = .roundedRect
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    let passwordField: UITextField = {
        let textField = UITextField()
        textField.placeholder = "Password"
        textField.borderStyle = .roundedRect
        textField.isSecureTextEntry = true
        textField.translatesAutoresizingMaskIntoConstraints = false
        return textField
    }()

    let loginButton: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("Login", for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false
        return button
    }()

    let forgotButton: UIButton = {
        let button = UIButton(type: .system)
        button.setTitle("Forgot Credentials", for: .normal)
        button.translatesAutoresizingMaskIntoConstraints = false
        return button
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // Add UI elements to the view
        view.addSubview(usernameField)
        view.addSubview(passwordField)
        view.addSubview(loginButton)
        view.addSubview(forgotButton)

        // Set up auto layout constraints
        NSLayoutConstraint.activate([
            // Username Field
            usernameField.topAnchor.constraint(equalTo: view.topAnchor, constant: 100),
            usernameField.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            usernameField.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),

            // Password Field
            passwordField.topAnchor.constraint(equalTo: usernameField.bottomAnchor, constant: 20),
            passwordField.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            passwordField.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),

            // Login Button
            loginButton.topAnchor.constraint(equalTo: passwordField.bottomAnchor, constant: 20),
            loginButton.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            loginButton.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),

            // Forgot Button
            forgotButton.topAnchor.constraint(equalTo: loginButton.bottomAnchor, constant: 20),
            forgotButton.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20),
            forgotButton.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20),
        ])
    }
}

This example creates and configures UITextField and UIButton instances, adds them to the view, and then sets up constraints using NSLayoutConstraint to define their positions and relationships. Adjust the constraints according to your layout preferences.