Example node creation handler for Neos that converts the given Asset Identifier into an Asset Object

ExampleNodeCreationHandler.php

<?php
namespace UseYourOwn\Namespace\NodeCreationHandler;

use Neos\ContentRepository\Domain\Model\NodeInterface;
use Neos\Flow\Annotations as Flow;
use Neos\Flow\Property\PropertyMapper;
use Neos\Flow\ResourceManagement\ResourceManager;
use Neos\Media\Domain\Model\Asset;
use Neos\Media\Domain\Model\AssetInterface;
use Neos\Neos\Ui\NodeCreationHandler\NodeCreationHandlerInterface;

class ExampleNodeCreationHandler implements NodeCreationHandlerInterface
{
    /**
     * Handle creation dialog asset
     *
     * @param NodeInterface $node The newly created node
     * @param array $data incoming data from the creationDialog
     * @return void
     */
    public function handle(NodeInterface $node, array $data)
    {
        if (isset($data['assetPropertyName'])) {
            try {
                // If you just want to set the asset as a nodes property
                $node->setProperty('assetPropertyName', $data['assetPropertyName']);

                // If you need to get the resource uri for some reason
                $propertyMapper = new PropertyMapper();
                $assetObject = $propertyMapper->convert($data['assetPropertyName'], Asset::class);

                if ($assetObject instanceof AssetInterface) {
                    $resourceManager = new ResourceManager();
                    $assetResourceUri = $resourceManager->getPublicPersistentResourceUri($assetObject->getResource());

                    // Do whatever you want with $assetResourceUri
                    // ...
                }
            } catch (\Exception $e) {
                // Log exception or do whatever is needed...
            }
        }
    }
}