Integrate Flexform for Plugin TYPO3 (6.2, too)

ExampleController.php

<?php
namespace Vendor\Exampleext\Controller;

/* ... */

/**
 * ExampleController
 */
class ExampleController extends \TYPO3\CMS\Extbase\Mvc\Controller\ActionController {

	/**
	 * action list
	 *
	 * @return void
	 */
	public function listAction() {
		$this->view->assign('program', $this->settings['number']);
		// ...
	}

ext_tables.php

<?php
// ....

// Include flex forms
$pluginSignature = str_replace('_', '', $_EXTKEY) . '_' . 'LOWERCASE_PLUGINNAME'; // from registerPlugin(...)
$TCA['tt_content']['types']['list']['subtypes_addlist'][$pluginSignature] = 'pi_flexform';
\TYPO3\CMS\Core\Utility\ExtensionManagementUtility::addPiFlexFormValue(
	$pluginSignature,
	'FILE:EXT:' . $_EXTKEY . '/Configuration/FlexForms/setup.xml'
);

setup.xml

<?xml version="1.0" encoding="UTF-8"?>
<T3DataStructure>
	<sheets>
		<sDEF>
			<ROOT>
				<TCEforms>
					<sheetTitle>Flexform für Typo3 Extbase</sheetTitle>
				</TCEforms>
				<type>array</type>
				<el>
					<switchableControllerActions>
						<TCEforms>
							<label>Standardaktion des Plugins</label>
							<config>
								<type>select</type>
								<items>
									<numIndex index="0">
										<numIndex index="0">Listenansicht</numIndex>
										<numIndex index="1">MyController->list</numIndex>
									</numIndex>
									<numIndex index="1">
										<numIndex index="0">Einzelansicht</numIndex>
										<numIndex index="1">MyController->show;MyController->edit</numIndex>
									</numIndex>
								</items>
							</config>
						</TCEforms>
					</switchableControllerActions>
					<settings.program>
						<TCEforms>
							<label>LLL:EXT:szshareform/Resources/Private/Language/locallang_db.xlf:tx_szshareform_domain_model_story.program</label>
							<config>
								<type>select</type>
								<foreign_table>tx_szshareform_domain_model_program</foreign_table>
								<minitems>0</minitems>
								<maxitems>1</maxitems>
							</config>
						</TCEforms>
					</settings.program>
				</el>
			</ROOT>
		</sDEF>
	</sheets>
</T3DataStructure>