PHP - access values inside an object : I have a requirement to access value inside an object return from an API response in PHP. 
API response 

    $res = {
    	"data": {
    		"first_name": "Dany",
    		"last_name": "mate",
    		"id": "1379933133290837510",
    		"image": {
    			"60x60": {
    				"url": "https://s-media-cache-ak0.pinimg.com/avatars/dtest_1438666564_60.jpg",
    				"width": 60,
    				"height": 60
    			}
    		}
    	}
    }

How to access the parameters "first_name" & "url"? Your help is much appreciated. I have tried to convert the response in to an array but not worked 

    $array = get_object_vars($res);
I don't know is it the correct way to do this?