您使用XCTest API方法提取了该值。
正确的方法可以在EarlGrey常见问题解答https://github.com/google/EarlGrey/blob/master/docs/faq.md中找到

// Swift
//
// Must use a wrapper class to force pass by reference in Swift 3 closures.
// inout params cannot be modified within closures. http://stackoverflow.com/a/28252105
open class Element {
  var text = ""
}

/*
 *  Example Usage:
 *
 *  let element = Element()
 *  domainField.performAction(grey_replaceText("hello.there"))
 *             .performAction(grey_getText(element))
 *
 *  GREYAssertTrue(element.text != "", reason: "get text failed")
 */
public func grey_getText(_ elementCopy: Element) -> GREYActionBlock {
  return GREYActionBlock.action(withName: "get text",
  constraints: grey_respondsToSelector(#selector(getter: UILabel.text))) { element,
                                                                           errorOrNil -> Bool in
        let elementObject = element as? NSObject
        let text = elementObject?.perform(#selector(getter: UILabel.text),
                                          with: nil)?.takeRetainedValue() as? String
        elementCopy.text = text ?? ""
        return true
    }
}

终于，查出来了！
使用application.navigationBars["Navigation bar Name"].searchFields["Label of the textField / Search Bar"].value
这将从文本字段中提取值。需要注意的是，检索到的值将为**“any”**类型

Can anyone write the below code with objective-c?

// Swift
//
// Must use a wrapper class to force pass by reference in Swift 3 closures.
// inout params cannot be modified within closures. http://stackoverflow.com/a/28252105
open class Element {
  var text = ""
}

/*
 *  Example Usage:
 *
 *  let element = Element()
 *  domainField.performAction(grey_replaceText("hello.there"))
 *             .performAction(grey_getText(element))
 *
 *  GREYAssertTrue(element.text != "", reason: "get text failed")
 */
public func grey_getText(_ elementCopy: Element) -> GREYActionBlock {
  return GREYActionBlock.action(withName: "get text",
  constraints: grey_respondsToSelector(#selector(getter: UILabel.text))) { element,
                                                                           errorOrNil -> Bool in
        let elementObject = element as? NSObject
        let text = elementObject?.perform(#selector(getter: UILabel.text),
                                          with: nil)?.takeRetainedValue() as? String
        elementCopy.text = text ?? ""
        return true
    }
}