基于@Ted的回答，我使用了这个扩展:

extension XCTestCase {

    // Based on https://stackoverflow.com/a/33855219
    func waitFor<T>(object: T, timeout: TimeInterval = 5, file: String = #file, line: UInt = #line, expectationPredicate: @escaping (T) -> Bool) {
        let predicate = NSPredicate { obj, _ in
            expectationPredicate(obj as! T)
        }
        expectation(for: predicate, evaluatedWith: object, handler: nil)

        waitForExpectations(timeout: timeout) { error in
            if (error != nil) {
                let message = "Failed to fulful expectation block for \(object) after \(timeout) seconds."
                let location = XCTSourceCodeLocation(filePath: file, lineNumber: line)
                let issue = XCTIssue(type: .assertionFailure, compactDescription: message, detailedDescription: nil, sourceCodeContext: .init(location: location), associatedError: nil, attachments: [])
                self.record(issue)
            }
        }
    }

}

你可以这样用

let element = app.staticTexts["Name of your element"]
waitFor(object: element) { $0.exists }

它还允许等待元素消失或任何其他属性更改(通过使用适当的块)

waitFor(object: element) { !$0.exists } // Wait for it to disappear

此外，你可以只睡觉:

sleep(10)

因为uitest在另一个进程中运行，所以这是可行的。我不知道这有多明智，但确实有效。

这将创建一个延迟，而不会使线程进入睡眠状态或在超时时抛出错误:

let delayExpectation = XCTestExpectation()
delayExpectation.isInverted = true
wait(for: [delayExpectation], timeout: 5)

因为期望颠倒了，它会悄悄超时。

从Xcode 8.3开始，我们可以使用XCTWaiter http://masilotti.com/xctest-waiting/

func waitForElementToAppear(_ element: XCUIElement) -> Bool {
    let predicate = NSPredicate(format: "exists == true")
    let expectation = expectation(for: predicate, evaluatedWith: element, 
                                  handler: nil)

    let result = XCTWaiter().wait(for: [expectation], timeout: 5)
    return result == .completed
}

另一个技巧是写一个等待函数，感谢John Sundell给我演示了它

extension XCTestCase {

  func wait(for duration: TimeInterval) {
    let waitExpectation = expectation(description: "Waiting")

    let when = DispatchTime.now() + duration
    DispatchQueue.main.asyncAfter(deadline: when) {
      waitExpectation.fulfill()
    }

    // We use a buffer here to avoid flakiness with Timer on CI
    waitForExpectations(timeout: duration + 0.5)
  }
}

然后像这样使用它

func testOpenLink() {
  let delegate = UIApplication.shared.delegate as! AppDelegate
  let route = RouteMock()
  UIApplication.shared.open(linkUrl, options: [:], completionHandler: nil)

  wait(for: 1)

  XCTAssertNotNil(route.location)
}

睡眠会阻塞线程

线程阻塞时不发生运行循环处理。

你可以使用waitForExistence

let app = XCUIApplication()
app.launch()

if let label = app.staticTexts["Hello, world!"] {
label.waitForExistence(timeout: 5)
}

Xcode 9 引入了XCTWaiter的新技巧

测试用例显式等待

wait(for: [documentExpectation], timeout: 10)

服务员实例委托测试

XCTWaiter(delegate: self).wait(for: [documentExpectation], timeout: 10)

服务生类返回结果

let result = XCTWaiter.wait(for: [documentExpectation], timeout: 10)
switch(result) {
case .completed:
    //all expectations were fulfilled before timeout!
case .timedOut:
    //timed out before all of its expectations were fulfilled
case .incorrectOrder:
    //expectations were not fulfilled in the required order
case .invertedFulfillment:
    //an inverted expectation was fulfilled
case .interrupted:
    //waiter was interrupted before completed or timedOut
}

示例使用

在Xcode 9之前

Objective - C

- (void)waitForElementToAppear:(XCUIElement *)element withTimeout:(NSTimeInterval)timeout
{
    NSUInteger line = __LINE__;
    NSString *file = [NSString stringWithUTF8String:__FILE__];
    NSPredicate *existsPredicate = [NSPredicate predicateWithFormat:@"exists == true"];

    [self expectationForPredicate:existsPredicate evaluatedWithObject:element handler:nil];

    [self waitForExpectationsWithTimeout:timeout handler:^(NSError * _Nullable error) {
        if (error != nil) {
            NSString *message = [NSString stringWithFormat:@"Failed to find %@ after %f seconds",element,timeout];
            [self recordFailureWithDescription:message inFile:file atLine:line expected:YES];
        }
    }];
}

使用

XCUIElement *element = app.staticTexts["Name of your element"];
[self waitForElementToAppear:element withTimeout:5];

斯威夫特

func waitForElementToAppear(element: XCUIElement, timeout: NSTimeInterval = 5,  file: String = #file, line: UInt = #line) {
        let existsPredicate = NSPredicate(format: "exists == true")

        expectationForPredicate(existsPredicate,
                evaluatedWithObject: element, handler: nil)

        waitForExpectationsWithTimeout(timeout) { (error) -> Void in
            if (error != nil) {
                let message = "Failed to find \(element) after \(timeout) seconds."
                self.recordFailureWithDescription(message, inFile: file, atLine: line, expected: true)
            }
        }
    }

使用

let element = app.staticTexts["Name of your element"]
self.waitForElementToAppear(element)

or

let element = app.staticTexts["Name of your element"]
self.waitForElementToAppear(element, timeout: 10)

源