Ok thanks to all of u guys for your answers.
I've made some changing but i still can't display my array ...
Look at what i've done :
$prog = array();
$i=0;
while($row = $get_programmation->fetch_assoc()){
$prog[$i] = $row;
$i++;
}
echo json_encode($prog);
I would have this a result like this : {"id":"0","artist":"xxxx", .... etc} and then use it in my iOS app to display what i want.