In XCUITests, how to wait for existence of either of two ui elements

Inspired by http://masilotti.com/ui-testing-tdd/, you don't have to rely on XCTWaiter. You can simply run a loop and test whether one of them exists.

/// Waits for either of the two elements to exist (i.e. for scenarios where you might have/// conditional UI logic and aren't sure which will show)////// - Parameters:///   - elementA: The first element to check for///   - elementB: The second, or fallback, element to check for/// - Returns: the element that existed@discardableResultfunc waitForEitherElementToExist(_ elementA: XCUIElement, _ elementB: XCUIElement) -> XCUIElement? {    let startTime = NSDate.timeIntervalSinceReferenceDate    while (!elementA.exists && !elementB.exists) { // while neither element exists        if (NSDate.timeIntervalSinceReferenceDate - startTime > 5.0) {            XCTFail("Timed out waiting for either element to exist.")            break        }        sleep(1)    }    if elementA.exists { return elementA }    if elementB.exists { return elementB }    return nil}

then you could just do:

let foundElement = waitForEitherElementToExist(elementA, elementB)if foundElement == elementA {    // e.g. if it's a button, tap it} else {    // element B was found}

lagoman's answer is absolutely correct and great. I needed wait on more than 2 possible elements though, so I tweaked his code to support an Array of XCUIElement instead of just two.

@discardableResultfunc waitForAnyElement(_ elements: [XCUIElement], timeout: TimeInterval) -> XCUIElement? {    var returnValue: XCUIElement?    let startTime = Date()        while Date().timeIntervalSince(startTime) < timeout {        if let elementFound = elements.first(where: { $0.exists }) {            returnValue = elementFound            break        }        sleep(1)    }    return returnValue}

which can be used like

let element1 = app.tabBars.buttons["Home"]let element2 = app.buttons["Submit"]let element3 = app.staticTexts["Greetings"]foundElement = waitForAnyElement([element1, element2, element3], timeout: 5)// do whatever checks you may wantif foundElement == element1 {     // code}

NSPredicate supports OR predicates too.

For example I wrote something like this to ensure my application is fully finished launching before I start trying to interact with it in UI tests. This is checking for the existence of various landmarks in the app that I know are uniquely present on each of the possible starting states after launch.

extension XCTestCase {  func waitForLaunchToFinish(app: XCUIApplication) {    let loginScreenPredicate = NSPredicate { _, _ in      app.logInButton.exists    }    let tabBarPredicate = NSPredicate { _, _ in      app.tabBar.exists    }    let helpButtonPredicate = NSPredicate { _, _ in      app.helpButton.exists    }    let predicate = NSCompoundPredicate(      orPredicateWithSubpredicates: [        loginScreenPredicate,        tabBarPredicate,        helpButtonPredicate,      ]    )    let finishedLaunchingExpectation = expectation(for: predicate, evaluatedWith: nil, handler: nil)    wait(for: [finishedLaunchingExpectation], timeout: 30)  }}

In the console while the test is running there's a series of repeated checks for the existence of the various buttons I want to check for, with a variable amount of time between each check.

t = 13.76s Wait for com.myapp.name to idle

t = 18.15s Checking existence of "My Tab Bar" Button

t = 18.88s Checking existence of "Help" Button

t = 20.98s Checking existence of "Log In" Button

t = 22.99s Checking existence of "My Tab Bar" Button

t = 23.39s Checking existence of "Help" Button

t = 26.05s Checking existence of "Log In" Button

t = 32.51s Checking existence of "My Tab Bar" Button

t = 16.49s Checking existence of "Log In" Button

And voila, now instead of waiting for each element individually I can do it concurrently.

This is very flexible of course, since you can add as many elements as you want, with whatever conditions you want. And if you want a combination of OR and AND predicates you can do that too with NSCompoundPredicate. This can easily be adapted into a more generic function that accepts an array of elements like so:

func wait(for elements: XCUIElement...) { … }

Could even pass a parameter that controls whether it uses OR or AND.