php - Accessing object property with variable -

i have object full of arrays, able change element in array code

$i = 0; $object->property[$i] = "some value";

however following code not change value , returns no errors.

 $i = 0;  $propertyname = "property";  $object->$propertyname[$i] = "some value";

try:

 $i = 0;  $propertyname = "property";  $object->{$propertyname}[$i] = "some value";

And