Drupal 7: create custom content type in custom module

customodule.install

<?php

/**
 * Implements hook_install().
 */
function customodule_install() {
  node_types_rebuild();
  $types = node_type_get_types();
  node_add_body_field($types['my_content_type']); 
  add_custom_fields(); 
}

/*
 * Add extra fields.
 */
function add_custom_fields() {
  foreach (_customodule_installed_fields() as $field) {
    field_create_field($field);
  }
  foreach (_customodule_installed_instances() as $fieldinstance) {
    $fieldinstance['entity_type'] = 'node';
    $fieldinstance['bundle'] = 'my_content_type';
    field_create_instance($fieldinstance);
  }
}

/*
 * Define the fields.
 */
function _customodule_installed_fields() {
  $t = get_t();
  
  return array(
    'customodule_textfield1' => array(
      'field_name' => 'customodule_textfield1',
      'label' => $t('Custom text field 1'),
      'type' => 'text',
    ),
    'customodule_textfield2' => array(
      'field_name' => 'customodule_textfield2',
      'label' => $t('Custom text field 2'),
      'type' => 'text',
    ),
  );
}

/*
 * Define the field instances.
 */
function _customodule_installed_instances() {
  $t = get_t();
    
  return array(
    'customodule_textfield1' => array(
      'field_name' => 'customodule_textfield1',
      'type' => 'text',
      'label' => $t('Custom text field 1'),
      'widget' => array(
        'type' => 'text_textfield',
      ),
      'display' => array(
        'example_node_list' => array(
          'label' => $t('Custom text field 1'),
          'type' => 'text',
        ),
      ),
    ),
    'customodule_textfield2' => array(
      'field_name' => 'customodule_textfield2',
      'type' => 'text',
      'label' => $t('Custom text field 2'),
      'widget' => array(
        'type' => 'text',
      ),
      'display' => array(
        'example_node_list' => array(
          'label' => $t('Custom text field 2'),
          'type' => 'text',
        ),
      ),
    ),
  );
}

/**
 * Implements hook_uninstall().
 *
 * If needed, remove all 'my_content_type' node created when
 * this module is uninstalled.
 */
function customodule_uninstall() {
    $new_ct = 'my_content_type';

    $sql = 'SELECT nid FROM {node} n WHERE n.type = :type';
    $result = db_query($sql, array(':type' => $new_ct));
    
    $nodeids = array();
    foreach ($result as $row) {
        $nodeids[] = $row->nid;
    }
    
    node_delete_multiple($nodeids);
    delete_custom_fields();
    
    node_type_delete($new_ct);
    field_purge_batch(500);
}

function delete_custom_fields() {
    foreach (array_keys(_customodule_installed_fields()) as $field) {
        field_delete_field($field);
    }
    $instances = field_info_instances('node', 'my_content_type');
    foreach ($instances as $instance_name => $fieldinstance) {
        field_delete_instance($fieldinstance);
    }
}

customodule.module

/**
 * Implements hook_node_info()
 */
function customodule_node_info() {
  return array(
    'my_content_type' => array(
      'name' => t('My content type'),
      'base' => 'my_content_type',
      'description' => t('A description for this content type'),
      'has_title' => TRUE,
    )
  );
}

/**
 * Implement hook_form()
 */
function my_content_type_form($node, $form_state) {
  return node_content_form($node, $form_state);
}