view&update custom fields in the [ultimatemember_account] page

index.php

<?php
add_action('um_after_account_general', 'showUMExtraFields', 100);

function showUMExtraFields() {
  $id = um_user('ID');
  $output = '';
  $names = array('birth_date');

  $fields = array(); 
  foreach( $names as $name ) {
	  $fields[ $name ] = UM()->builtin()->get_specific_field( $name );
  }
	
	
    
  $fields = apply_filters('um_account_secure_fields', $fields, $id);
  foreach( $fields as $key => $data ) {
	  $output .= UM()->fields()->edit_field( $key, $data );
  }
    

  echo $output;
}

add_action('um_account_pre_update_profile', 'getUMFormData', 100);

function getUMFormData(){
  $id = um_user('ID');
  $names = array('birth_date');

  foreach( $names as $name ) {
	  update_user_meta( $id, $name, $_POST[$name] );
  }
    
}