PHP random array unique multi SOLVED

/*Original Array*/
$arrayIDs = ['a','aa','bb','cc'];
/*Result*/
$randomArray = [];
/*number unique*/
$numberRandom = 4;
if(count($arrayIDs)> $numberRandom){
while(count($randomArray) < $numberRandom) {
  $randomKey = mt_rand(0, count($arrayIDs)-1);
  $randomArray[$randomKey] = $arrayIDs[$randomKey];
}
}else{
$randomArray = $arrayIDs;
}