PHP相当于Javascript“for（x in y）”

I am wondering what is the equivalent of "for in(x in y)" of javascript in PHP? I've seen this code from other website with the same functionalities of my program but i want it to be converted into php.

Like for this javascript code:

function get_tat_friends(){
    var ar_friends = []; ar_fr_info = [];
    FB.api('me/photos?type=uploaded&fields=likes,comments',function(data){
        obj = data['data'];
        for(x in obj){
          if(obj[x]['likes'] != null){
            obj_like = obj[x]['likes']['data'];
            for(y in obj_like){
              if(ar_friends[obj_like[y]['id']] == null){
                ar_friends[obj_like[y]['id']] = 1;
                ar_fr_info[obj_like[y]['id']] = obj_like[y]['name'];
              }else{
                ar_friends[obj_like[y]['id']] += 1;
                ar_fr_info[obj_like[y]['id']] = obj_like[y]['name'];
              }
            }
          }
          if(obj[x]['comments'] != null){
            obj_like = obj[x]['comments']['data'];
            for(y in obj_like){
              if(ar_friends[obj_like[y]['from']['id']] == null){
                ar_friends[obj_like[y]['from']['id']] = 1;
                ar_fr_info[obj_like[y]['from']['id']] = obj_like[y]['from']['name'];
              }else{
                ar_friends[obj_like[y]['from']['id']] += 2;
                ar_fr_info[obj_like[y]['from']['id']] = obj_like[y]['from']['name'];
              } 
            }
          }
        }
        ar_friends = getSortedKeys(ar_friends);
        //delete user_id
          var index = ar_friends.indexOf(user_id);
          if (index >= 0) {
            ar_friends.splice( index, 1 );
          }

        //call done function
        done_load_friends(ar_friends,ar_fr_info);
    })
}

I already tried to do this but it doesn't work:

obj = data['data'];
for($x in obj){
}

Take a look at PHP documentation foreach loop:

foreach(array_expression as $value){
    statement
}

For an associative array, it's

foreach($array as $key => $value) {
    ...
}

If you have an object, you can get an associative array of its public properties with get_object_vars, so you can write:

foreach (get_object_vars($obj) as $key => $value) {
    ...
}