Could you explain what the iOS Software Development Kit is and how it is used in developing applications for iPhone and iPad?

iOS Software Development Kit (SDK) is a set of tools, libraries, and documentation provided by Apple for developing applications for iPhone and iPad. The SDK includes APIs for working with the interface, multimedia, networking, sensors, and other device capabilities.

Developers use the iOS SDK along with Swift or Objective-C languages and the Xcode environment to create, test, and debug applications. The SDK provides access to system functions and simplifies integration with the iOS platform.

An example of using the SDK is creating a button and handling its press in Swift:

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()

        let button = UIButton(type: .system)
        button.setTitle("Press me", for: .normal)
        button.addTarget(self, action: #selector(buttonTapped), for: .touchUpInside)
        button.frame = CGRect(x: 100, y: 100, width: 100, height: 50)
        view.addSubview(button)
    }

    @objc func buttonTapped() {
        print("Button pressed")
    }
}