How have you implemented testing your solutions at your previous job?

For testing iOS applications, I used XCTest — the standard framework for unit testing in Xcode. I wrote unit tests to verify the logic of models and services, as well as UI tests to check interaction with the interface.

Example of a simple unit test:

import XCTest
@testable import MyApp

class UserServiceTests: XCTestCase {
    func testUserCreation() {
        let userService = UserService()
        let user = userService.createUser(name: "Ivan")
        XCTAssertEqual(user.name, "Ivan")
    }
}

I also used mock objects to isolate the components under test and automated test runs through a CI system.