BeforeClass in XCTestCase in Swift

I am testing my application's interface, using Swift 3 and I use xCode 8 .

However, I need to make a user registration before starting my test cases and when I finish all the tests I must delete the created user, in order not to affect the database.

I see that it is possible to make an equivalent of beforeClass and afterClass of Android in iOS . Apparently, just overwrite the class method setUp() and tearDown() .

How to run one-time setup code before executing any XCTest

However, I could not understand how to put the code that I need to run in order to create my user. Is there any way to access the code of my application? o Do I need to register my user through the interface?

I enclose my current code:

class LoginUITests: XCTestCase {
let app = XCUIApplication()

override class func setUp() {
    super.setUp()
    print("setUp - Se ejecuta una vez, antes de TODOS los casos de prueba")
    // Called once before all tests are run
    // Intento ejecutar el registro de un usuario al menos por medio de 
    // la interfaz
    // registerUser()
}

override class func tearDown() {
    super.setUp()
    print("tearDown - Se ejecuta una vez, despues de TODOS los casos de prueba")
    // Called once after all tests are run
    // Intento ejecutar el unregister de un usuario al menos por medio de 
    // la interfaz
    // unRegisterUser()
}

override func setUp() {
    super.setUp()
    // In UI tests it is usually best to stop immediately when a failure occurs.
    continueAfterFailure = false
    app.launch()
    XCUIDevice.shared().orientation = .portrait
    app.tabBars.buttons["Generals"].tap()
    XCTAssertTrue(app.tables.cells.staticTexts["Identificate para sincronizar tus conversaciones"].exists)
    app.tables.staticTexts["Identificate para sincronizar tus conversaciones"].tap()
}

override func tearDown() {
    // Put teardown code here. This method is called after the invocation of each test method in the class.
    super.tearDown()
    let tabBarsQuery = app.tabBars
    if (tabBarsQuery.buttons.count >= 4){
        tabBarsQuery.buttons["Yo"].tap()
        app.scrollViews.otherElements.buttons["logOut"].tap()
    } else {
        print("No hay sesión en curso")
    }
}

func registerUser(){
    let dict : [String:Any]  = getDictionary()!
    let defaultEmail : String = dict["defaultEmail"] as! String
    let defaultName : String = dict["defaultName"] as! String
    let defaultPassword : String = dict["defaultPassword"] as! String
    let app = XCUIApplication()

    app.launch()
    XCUIDevice.shared().orientation = .portrait
    app.tabBars.buttons["Generals"].tap()
    XCTAssertTrue(app.tables.cells.staticTexts["Identificate para sincronizar tus conversaciones"].exists)
    app.tables.staticTexts["Identificate para sincronizar tus conversaciones"].tap()

    let tabBarsQuery = app.tabBars
    let emailTextField = app.textFields["email"]
    emailTextField.tap()
    emailTextField.typeText(defaultEmail)
    app.typeText("\n")
    let registerButton = app.buttons["register"]
    registerButton.tap()
    let userNameTextField = app.textFields["username"]
    let passwordTextField = app.secureTextFields["password"]
    let repeatPassTextField = app.secureTextFields["repeatPassword"]
    //Ingresamos campos para el registro
    userNameTextField.tap()
    userNameTextField.typeText(defaultName)
    app.typeText("\n")
    passwordTextField.tap()
    passwordTextField.typeText(defaultPassword)
    app.typeText("\n")
    repeatPassTextField.tap()
    repeatPassTextField.typeText(defaultPassword)
    app.typeText("\n")
    registerButton.tap()
    tabBarsQuery.buttons["Generals"].tap()
    XCTAssertFalse(app.tables.cells.staticTexts["Identificate para sincronizar tus conversaciones"].exists)
}

func unRegisterUser(){
    //Autenticar al usuario 
    //Posteriormente, darlo de baja
}

func testLoginEmail(){
    //....
}

func testLoginInvalidEmail(){
    //...
}

When I wanted to invoke registerUser() , I necessarily had to instantiate my class LoginUITests , then put: LoginUITests().registerUser() , but this also did not work so I could make a record before all my tests.

Is the implementation of setUp() and tearDown() correct, or am I failing something?