What types of tests would you choose for initial verification of an already developed product?

For initial verification of the developed product's operability, the following types of tests are usually chosen:

• Smoke tests — quick checks of the main functions to ensure that the application launches and key scenarios work without failures.

• Sanity tests — more narrowly focused checks after making changes to ensure that fixes did not break core functions.

• Functional tests — verify that individual application functions work according to requirements.

• UI tests (instrumental tests) — for iOS, this is XCTest UI, which checks user interaction with the interface.

For example, for iOS, you can write a simple XCTest that checks whether the main screen loads and displays the necessary elements:

func testMainScreenLoads() {
    let app = XCUIApplication()
    app.launch()
    XCTAssertTrue(app.buttons["StartButton"].exists)
}

Thus, the initial verification is a quick set of tests that allows you to ensure that the application as a whole works and is ready for more in-depth testing.