How do I download a file with php and the Amazon S3 sdk?

Both of these methods work for me. The first way seems more concise.

    $command = $s3->getCommand('GetObject', array(
       'Bucket' => 'bucket_name',
       'Key'    => 'object_name_in_s3'  
       'ResponseContentDisposition' => 'attachment; filename="'.$my_file_name.'"'
    ));

    $signedUrl = $command->createPresignedUrl('+15 minutes');
    echo $signedUrl;
    header('Location: '.$signedUrl);
    die();

Or a more wordy but still functional way.

    $object = $s3->getObject(array(
    'Bucket' => 'bucket_name',
    'Key'    => 'object_name_in_s3'   
    ));

    header('Content-Description: File Transfer');
    //this assumes content type is set when uploading the file.
    header('Content-Type: ' . $object->ContentType);
    header('Content-Disposition: attachment; filename=' . $my_file_name);
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');

    //send file to browser for download. 
    echo $object->body;

Got it to work by echo'ing out the content-type header before echo'ing the $object body.

$objInfo = $s3->get_object_headers('my_bucket', 'test.jpg');
$obj = $s3->get_object('my_bucket', 'test.jpg');

header('Content-type: ' . $objInfo->header['_info']['content_type']);
echo $obj->body;