title: Tap MKAnnotationView with XCTestCase
body: <p>I want to tap <code>MKAnnotationView</code> using my <code>XCTestCase</code> with UITest, so I have my mapView as a <code>XCUIElement</code>. I have no idea how to get annotations from mapView, I don't want to put fixed positions on this on the screens because it is tested on various devices. So I'm stuck on the
  <code>let mapView:XCUIElement = app.maps.elementBoundByIndex(0)</code></p>
  
  <p>Any ideas?</p>