Order multidimensional array recursively at each level in PHP

Question

I have an array of this form:

Array
(
    [first_level] => Array
        (
            [dir_3] => Array
                (
                    [subdir_1] => Array
                        (
                            [file_2.mp4] => stdClass Object
                                (
                                    [name] => file_2.mp4
                                )

                            [file_1.mp4] => stdClass Object
                                (
                                    [name] => file_1.mp4
                                )

                        )
                )
            [dir_1] => Array
                (
                    [subdir_2] => Array
                        (
                            [file_6.mp4] => stdClass Object
                                (
                                    [name] => file_6.mp4
                                )
                            [file_9.mp4] => stdClass Object
                                (
                                    [name] => file_9.mp4
                                )
                            [file_7.mp4] => stdClass Object
                                (
                                    [name] => file_7.mp4
                                )
                        )
                    [subdir_1] => Array
                        (
                            [file_8] => stdClass Object
                                (
                                    [name] => file_8.mp4
                                )

                        )
        )
    )
)

I need to order it like this:

Array
(
    [first_level] => Array
        (
            [dir_1] => Array
                (
                    [subdir_1] => Array
                        (
                            [file_8] => stdClass Object
                                (
                                    [name] => file_8.mp4
                                )
                        )
                    [subdir_2] => Array
                        (
                            [file_6.mp4] => stdClass Object
                                (
                                    [name] => file_6.mp4
                                )
                            [file_7.mp4] => stdClass Object
                                (
                                    [name] => file_7.mp4
                                )
                            [file_9.mp4] => stdClass Object
                                (
                                    [name] => file_9.mp4
                                )
                        )
        )
        [dir_3] => Array
                (
                    [subdir_1] => Array
                        (
                            [file_1.mp4] => stdClass Object
                                (
                                    [name] => file_1.mp4
                                )

                            [file_2.mp4] => stdClass Object
                                (
                                    [name] => file_2.mp4
                                )

                        )
                )
    )
)

I browsed through other similar questions, and I've been trying to solve it with usort but I couldn't get my head around it. :S

Any idea?

Answer 1

Use a recursive function:

// Note this method returns a boolean and not the array
function recur_ksort(&$array) {
   foreach ($array as &$value) {
      if (is_array($value)) recur_ksort($value);
   }
   return ksort($array);
}