An easier way to access UI elements or check for existence within a UI Test.

XCTestCase+Helper.swift

extension XCTestCase {
    var app: XCUIApplication { return XCUIApplication() }
    
    func checkExistenceOfElements(_ typesAndTexts: [(XCUIElement.ElementType, String)], timeout: TimeInterval = 3) {
        for (type, text) in typesAndTexts {
            checkExistenceOfElement(type, text, timeout: timeout)
        }
    }

    func checkExistenceOfElement(_ type: XCUIElement.ElementType, _ text: String, timeout: TimeInterval = 3) {
        XCTAssertTrue(element(ofType: type, withText: text, timeout: timeout).exists, "Element with text \"\(text)\" could not be found.")
    }
    
    /// Search for element in multiple locations within the view hierarchy
    func element(ofType type: XCUIElement.ElementType, withText text: String, timeout: TimeInterval = 3) -> XCUIElement {
        assert(type != .other, "It is not safe to use ElementType \"other\" in this helper method as it can create a recursive loop")

        let shouldOnlyUsePredicates: Bool = text.count > 128

        let inDescendants = app.descendants(matching: type).descendants(matching: type).matching(labelPredicate(forText: text)).firstMatch
        let closeMatch = app.descendants(matching: type).element(matching: labelPredicate(forText: text)).firstMatch

        var possibleElements: [XCUIElement] = [inDescendants, closeMatch]

        if !shouldOnlyUsePredicates {
            let inScrollView = app.scrollViews.otherElements.descendants(matching: type)[text]
            let inApp = app.descendants(matching: type)[text]
            let inTableView = app.tables.descendants(matching: type)[text]
            let inTabBar = app.tabBars.descendants(matching: type)[text]
            let inNavBar = app.navigationBars.descendants(matching: type)[text]
            let lastDitchEffort = app.staticTexts[text]

            possibleElements.append(contentsOf: [inScrollView, inApp, inTableView, inTabBar, inNavBar, lastDitchEffort])
        }

        let matchFilter: (XCUIElement) -> Bool = { $0.exists && $0.elementType == type }
        var elapsedTime: TimeInterval = 0

        while elapsedTime < timeout {

            if let validElement = possibleElements.lazy.filter(matchFilter).first {
                return validElement
            }
            usleep(200000) // sleep for .2 seconds
            elapsedTime += 0.2
        }

        return app.descendants(matching: type)["Intentionally returning an element that does not exist"]
    }

    /// Breaks down multi-line text for predicate use
    private func labelPredicate(forText text: String) -> NSPredicate {
        let linesOfText = text.components(separatedBy: "\n")
        var format = "label CONTAINS '\(linesOfText.first!)'"

        if linesOfText.count > 1 {
            for i in 1..<linesOfText.count where !linesOfText[i].isEmpty {
                format += " AND label CONTAINS '\(linesOfText[i])'"
            }
        }
        return NSPredicate(format: format)
    }
}

Example usage:

checkExistenceOfElements([
    (.navigationBar, "Make Payment"),
    (.textField, "Card Number, required"),
    (.button, "Take a photo to scan credit card number"),
    (.staticText, "Expiration Date"),
    (.image, "credit_card_icon")
])