[PHP] - Filter API object response

I've a code that will mark view all friends stories. But I want to check if my clients usernames is not their. then pause! Code: $storiesResponse = $login->getStoriesResponse(); if (strpos($storiesResponse, 'mzaboss') == false) { echo "mzaboss is not available! die! \n"; die; } else { foreach($storiesResponse->getFriendStories() as $friendStories){ $friendStoriesUsername = $friendStories->getUsername(); $storiesContainer = $friendStories->getStories(); foreach($storiesContainer as $storyContainer){ $story = $storyContainer->getStory(); echo "Mark as viewed story ID: " . $story->getId() . "\n"; $snapchat->markStoryViewed($story->getId()); } $account_id = $i + 1; // return true; } } } The API response: object(X\API\Response\Model\FriendStories)#14161 (2) { ["username":"X\API\Response\Model\FriendStories":private]=> string(7) "mzaboss" ["stories":"X\API\Response\Model\FriendStories":private]=> array(1) { [0]=> object(X\API\Response\Model\FriendStoryContainer)#14166 (2) { ["story":"X\API\Response\Model\FriendStoryContainer":private]=> object(X\API\Response\Model\Story)#14168 (16) { ["id":"X\API\Response\Model\Story":private]=> string(21) "mzaboss~1467880186851" ["username":"X\API\Response\Model\Story":private]=> string(7) "mzaboss" ["mature_content":"X\API\Response\Model\Story":private]=> bool(false) ["client_id":"X\API\Response\Model\Story":private]=> string(44) "MZABOSS~E02D10B1-9D0B-4698-A9E8-EB43F4D4281D" ["timestamp":"X\API\Response\Model\Story":private]=> int(1467880186851) ["media_id":"X\API\Response\Model\Story":private]=> string(16) "6315314297815040" ["media_key":"X\API\Response\Model\Story":private]=> string(44) "Z0xvmwDCcY3leDm3DC4QPdOGh+9va4iYEbb0Zs0YkUQ=" ["media_iv":"X\API\Response\Model\Story":private]=> string(24) "C+omyS1YQncoraMO0iY4jg==" ["thumbnail_iv":"X\API\Response\Model\Story":private]=> string(24) "WB4E4e0w0ToXZOqBI+z87w==" ["media_type":"X\API\Response\Model\Story":private]=> int(0) ["time":"X\API\Response\Model\Story":private]=> float(3) ["caption_text_display":"X\API\Response\Model\Story":private]=> NULL ["zipped":"X\API\Response\Model\Story":private]=> bool(false) ["time_left":"X\API\Response\Model\Story":private]=> int(86296613) ["needs_auth":"X\API\Response\Model\Story":private]=> bool(false) ["is_shared":"X\API\Response\Model\Story":private]=> bool(false) } ["viewed":"X\API\Response\Model\FriendStoryContainer":private]=> bool(false) } } } $storiesResponse is very long array objects. I want to find if "mzaboss" is in that array object response or not, if it exists then good, if it not there, then die.