ページがLikedかどうかを得るだけの簡単な関数

getliked.php

<?php

/**
 * likedを得るだけの簡単な関数
 */
function getLiked(){
	$signed_request = isset( $_POST["signed_request"] ) ? $_POST["signed_request"] : null;
	$json = json_decode( base64_decode( array_pop( explode( ".", $signed_request ) ) ) );
	if( isset( $json->page ) && isset( $json->page->liked ) ){
		return $json->page->liked;
	}
	return null;
}