code: public function save_custom_profile_fields( $user_id ) {
  
  		if ( 'POST' !== $_SERVER[ 'REQUEST_METHOD' ] || ! isset( $_POST[ 'iac_nonce' ] ) ) {
  			return;
  		}
  		if ( ! wp_verify_nonce( $_POST[ 'iac_nonce' ], 'iac_user_settings' ) ) {
  			return;
  		}
  
  		do_action(
  			'iac_save_user_settings',
  			$user_id,
  			isset( $_POST[ 'post_subscription' ] )
  				? $_POST[ 'post_subscription' ]
  				: NULL
  			,
  			isset( $_POST[ 'comment_subscription' ] )
  				? $_POST[ 'comment_subscription' ]
  				: NULL
  		);
  
  	}
docs: Save meta data from custom profile fields
  
  @wp-hook personal_options_update
  @wp-hook edit_user_profile_update
  
  @since  0.0.2
  @uses   current_user_can, update_user_meta
  
  @param  string $user_id
  
  @return void