Dynamically set the post type when creating a post

<?php
add_filter( 'af/form/editing/post_data', function ( $post_data, $form, $args ) {

  // Check if this is the correct form. If not, return the post data as is.
  if ( $form['key'] !== '{YOUR_FORM_KEY}' ) {
    return $post_data;
  }

  // Get the selected post type from the submitted form field
  // Replace 'post_type_selector' with your field name or field key
  $selected_post_type = af_get_field( 'post_type_selector' );

  // If the selected post type exists, set it for the post being created
  if ( $selected_post_type && post_type_exists( $selected_post_type ) ) {
    $post_data['post_type'] = sanitize_key( $selected_post_type );
  }

  return $post_data;

}, 10, 3 );