function focusTextInput(textFieldID: ?number) {
  if (currentlyFocusedID !== textFieldID && textFieldID !== null) {
    currentlyFocusedID = textFieldID;
    if (Platform.OS === "ios" || Platform.OS === "dom") {
      UIManager.focus(textFieldID);
    } else if (Platform.OS === "android") {
      UIManager.dispatchViewManagerCommand(
        textFieldID,
        UIManager.AndroidTextInput.Commands.focusTextInput,
        null
      );
    }
  }
}
@param {number} TextInputID id of the text field to focus
Focuses the specified text field
noop if the text field was already focused