Facebook PHP API

I am running this simple code:

<?php
$keyword = 'iPhone';
$graph_url = "https://graph.facebook.com/search?";
$graph_url .= "&type=post";
$graph_url .= "&q=$keyword";
$results = file_get_contents( $graph_url );

$json = json_decode($results);

foreach($json->data as $show ) {
echo '<img src="'.$show->picture.'" alt="some_text"/><br />';
echo $show->from->name . "<br />";
echo $show->message . "<br />";
echo $show->created_time . "<br />";
echo "<hr>";
}
?>

It is retrieving all facebook posts for the keyword 'iPhone' how come some of the content is empty and the facebook profile pictures don't display on all posts and how would I limit posts. How do I go about fixing this, anyone point me in the right direction?

<?php
$keyword = 'iPhone';
$graph_url = "https://graph.facebook.com/search?";
$graph_url .= "&type=post";
$graph_url .= "&q=$keyword";

//add these lines

 $graph_url .= "&fields=from,caption,created_time,picture";
 $graph_url .= "&limit=$number";

//

$results = file_get_contents( $graph_url );

$json = json_decode($results);

foreach($json->data as $show ) {
echo '<img src="'.$show->picture.'" alt="some_text"/><br />';
echo $show->from->name . "<br />";
echo $show->caption. "<br />";
echo $show->created_time . "<br />";
echo "<hr>";
}
?>