What are mocking and stubbing techniques for UIKit in Swift?

        // Example of mocking and stubbing in Swift with XCTest framework
        import XCTest
        import UIKit

        // Protocol to define the behavior of a network service
        protocol NetworkService {
            func fetchData() -> String
        }

        // Mock class to simulate the NetworkService
        class MockNetworkService: NetworkService {
            func fetchData() -> String {
                return "Mocked Data"
            }
        }

        class MyViewController: UIViewController {
            var networkService: NetworkService?

            func displayData() -> String {
                return networkService?.fetchData() ?? "No Data"
            }
        }

        class MyViewControllerTests: XCTestCase {
            func testDisplayData() {
                // Arrange
                let mockService = MockNetworkService()
                let viewController = MyViewController()
                viewController.networkService = mockService

                // Act
                let result = viewController.displayData()

                // Assert
                XCTAssertEqual(result, "Mocked Data")
            }
        }