bbp_is_user_subscribed( int $user_id,  $object_id )

function bbp_is_user_subscribed( $user_id = 0, $object_id = 0 ) {

	// Assume user is not subscribed
	$retval = false;

	// Setup ID's array
	$subscribed_ids = array();

	// User and object ID's are passed
	if ( ! empty( $user_id ) && ! empty( $object_id ) ) {

		// Get the post type
		$post_type = get_post_type( $object_id );

		// Post exists, so check the types
		if ( ! empty( $post_type ) ) {

			switch( $post_type ) {

				// Forum
				case bbp_get_forum_post_type() :
					$subscribed_ids = bbp_get_user_subscribed_forum_ids( $user_id );
					$retval         = bbp_is_user_subscribed_to_forum( $user_id, $object_id, $subscribed_ids );
					break;

				// Topic (default)
				case bbp_get_topic_post_type() :
				default :
					$subscribed_ids = bbp_get_user_subscribed_topic_ids( $user_id );
					$retval         = bbp_is_user_subscribed_to_topic( $user_id, $object_id, $subscribed_ids );
					break;
			}
		}
	}

	return (bool) apply_filters( 'bbp_is_user_subscribed', $retval, $user_id, $object_id, $subscribed_ids );
}