title: How to use a dynamic identifier to check for values of UI elements?
body: <p>I am getting started with UI testing with Xcode and I am trying to check for the value of a UITextField.
  I can easily do this by </p>
  
  <pre><code>XCTAssertTrue(app.staticTexts[@"value of string"].exists);
  </code></pre>
  
  <p>I do, however, want to do the very same thing with dynamic content. Ideally, I would need something like</p>
  
  <pre><code>NSString* requiredValue = "computed string";
  XCTAssertTrue(app.staticTexts[requiredValue].exists);
  </code></pre>
  
  <p>How can I implement this? I would greatly appreciated any hint or link to good resources that might answer this question.</p>