异步UI测试在Xcode 7 Beta 4中引入。要等待文本“Hello, world!”的标签出现，您可以执行以下操作:

let app = XCUIApplication()
app.launch()

let label = app.staticTexts["Hello, world!"]
let exists = NSPredicate(format: "exists == 1")

expectationForPredicate(exists, evaluatedWithObject: label, handler: nil)
waitForExpectationsWithTimeout(5, handler: nil)

关于UI测试的更多细节可以在我的博客上找到。

在我目前的公司，我们是这样做的:创建一个XCUIElement表达式期望(以创建一个通用的等待方法)。我们以以下方式来确保它是可维护的(有很多不同的期望，并且不想为此创建很多方法/特定的谓词。

斯威夫特5

基本方法

该表达式用于形成一个动态谓词值。我们可以从谓词创建xctnspredicateexpect，然后将其传递给XCTWaiter以显式等待。如果结果不是已完成，则失败并返回一条可选消息。

@discardableResult
func wait(
    until expression: @escaping (XCUIElement) -> Bool,
    timeout: TimeInterval = 15,
    message: @autoclosure () -> String = "",
    file: StaticString = #file,
    line: UInt = #line
) -> Self {
    if expression(self) {
        return self
    }

    let predicate = NSPredicate { _, _ in
        expression(self)
    }

    let expectation = XCTNSPredicateExpectation(predicate: predicate, object: nil)

    let result = XCTWaiter().wait(for: [expectation], timeout: timeout)

    if result != .completed {
        XCTFail(
            message().isEmpty ? "expectation not matched after waiting" : message(),
            file: file,
            line: line
        )
    }

    return self
}

使用

app.buttons["my_button"].wait(until: { $0.exists })
app.buttons["my_button"].wait(until: { $0.isHittable })

Keypaths

然后将其包装在一个方法中，其中keyPath和match值构成表达式。

@discardableResult
func wait<Value: Equatable>(
    until keyPath: KeyPath<XCUIElement, Value>,
    matches match: Value,
    timeout: TimeInterval = 15,
    message: @autoclosure () -> String = "",
    file: StaticString = #file,
    line: UInt = #line
) -> Self {
    wait(
        until: { $0[keyPath: keyPath] == match },
        timeout: timeout,
        message: message,
        file: file,
        line: line
    )
}

使用

app.buttons["my_button"].wait(until: \.exists, matches: true)
app.buttons["my_button"].wait(until: \.isHittable, matches: false)

然后可以包装该方法，其中匹配值对于我发现的最常见的用例始终为真。

使用

app.buttons["my_button"].wait(until: \.exists)
app.buttons["my_button"].wait(until: \.isHittable)

我写了一篇关于它的文章，并获得了完整的扩展文件:https://sourcediving.com/clean-waiting-in-xcuitest-43bab495230f

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

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)
}

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

iOS 11 / Xcode 9

<#yourElement#>.waitForExistence(timeout: 5)

这是一个伟大的替代所有自定义实现在这个网站!

一定要看看我的答案:https://stackoverflow.com/a/48937714/971329。在这里，我描述了一种替代等待请求的方法，它将大大减少测试运行的时间!