title: How to set an accessibilityIdentifier on a UITabBar's buttons
body: <p>Like the title states, how do you programmatically set the <code>accessibilityIdentifier</code> on a <code>UITabBar</code>'s buttons? I'm currently trying to set the <code>UITabBarItem</code>'s <code>accessibilityIdentifier</code> before adding it to the tab bar, but that doesn't seem to carry through to the button.</p>
  
  <p>How do you go about setting an <code>accessibilityIdentifier</code> on the actual buttons that are displayed on the page?</p>