Sort a multi-dim array by a column

I got ONE array which contains multiple array and a value with order which contains 1 2 3 4 5 6 7 8 etc ....

I can't change this structure

["Categ1"]=>
 array(3) {
   ["order"]=>
   string(1) "5"
   [0]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
   [1]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
 }
 ["Categ2"]=>
 array(3) {
   ["order"]=>
   string(1) "2"
   [0]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
   [1]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
 }

What I need is pretty simple but I can't find a solution :

["Categ2"]=>
array(3) {
  ["order"]=>
  string(1) "2"
  [0]=>
  array(5) {
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    NULL
  }
  [1]=>
  array(5) {
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    string(x) "xxx"
    ["content"]=>
    NULL
  }
}
["Categ1"]=>
 array(3) {
   ["order"]=>
   string(1) "5"
   [0]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
   [1]=>
   array(5) {
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     string(x) "xxx"
     ["content"]=>
     NULL
   }
 }

Just a simple order with the order value.

You need to define a custom sorting function and hand it over to a php sort function. e.g. uasort

This minimalistic example shows it pretty good.

$cats = [
    'cat1' => [
        "order" => 5,
        ["foo" => "bar"]
    ],
    'cat2' => [
        "order" => 3,
        ["foo" => "bar"]
    ]
];

uasort($cats, function($a, $b){
    return $a['order'] > $b['order'];
});

var_dump($cats);

Will output:

 array (size=2)   
 'cat2' => 
    array (size=2)
      'order' => int 3
      0 => 
        array (size=1)
          'foo' => string 'bar' (length=3)   
 'cat1' => 
    array (size=2)
      'order' => int 5
      0 => 
        array (size=1)
          'foo' => string 'bar' (length=3)