在php中的foreach循环中迭代对象的对象

Question

I have a function that is being passed an object that contains other objects that have permission ids in them. I need those permission ids in a foreach loop. Most of my tries give me an array to string conversion or a call to a non-object error.

A formatted var_dump of $permission looks like this...

array (size=1)
  0 => 
    array (size=2)
      0 => 
        object(stdClass)[9]
          public 'permission_id' => string '1' (length=1)
      1 => 
        object(stdClass)[11]
          public 'permission_id' => string '2' (length=1)

//My function starts off like this...

function checkPermission($permission) {
  $db = DB::getInstance();
  global $user;

  foreach($permission as $key=>$value){

I need to figure out how to setup that foreach loop where every round of the loop passes in that permission_id from the var_dump above.