A sample project about UI testing using "Page Object Model" technique.
An article can be found on LinkedIn.

Overview

The main idea is to incapsulate screen logic into an object called PageObject. To be used with XCTest framework it was implemented as follows:

class PageObject {

    struct Consts {
        static let defaultTimeout: TimeInterval = 1.0
    }

    let application: XCUIApplication

    required init(application: XCUIApplication) {
        self.application = application
    }

    @discardableResult
    func verify(timeout: TimeInterval = Consts.defaultTimeout) throws -> Self {
        return self
    }

}

PageObject is a root class. Subclasses are supposed to override verify method and provide extra actions that are allowed on associated page.

class WelcomePageObject: PageObject {

    @discardableResult
    override func verify(timeout: TimeInterval = Consts.defaultTimeout) throws -> Self {
        try [
            self.application.staticTexts.element(label: "Welcome"),
            self.application.staticTexts.element(
                label: "This is a simple questionnaire app to demonstrate the power of Page Object pattern."
            ),
            self.application.staticTexts.element(label: "Tap 'Start' to begin."),
            self.application.buttons.element(label: "Start"),
        ].throwIfDoesNotExist(timeout: timeout)
        return self
    }

    @discardableResult
    func start(timeout: TimeInterval = Consts.defaultTimeout) throws -> Question1PageObject {
        try self.application.buttons.element(label: "Start").tapOrThrow(timeout: timeout)
        return Question1PageObject(application: self.application)
    }
    
}