The RecursiveIteratorIterator makes it super easy to traverse a nested array.

Here is an example though the docs are pretty clear there. For me it was in a class so I defined the array keys at the top of the Class

    protected $merged_profile_options = [];
    protected $data_values = [
        'browser' => null,
        'name' => null,
        'version' => null,
        'platform' => null,
        'base_url' => null,
        'repo' => null,
        'filename' => null,
        'branch' => null,
        'status' => null,
        'user_uuid' => null,
        'remote_job_id' => null,
        'job_id'  => null,
    ];

Then later on iterated over that array.

    protected function setAllDataValues() {
        $traverse = new \RecursiveIteratorIterator(
            new \RecursiveArrayIterator($this->merged_profile_options));
        foreach($traverse as $key=>$value)
        {
            if(array_key_exists($key, $this->data_values))
            {
                $this->setDataValues($key, $value);
            }
        }
    }

    public function setDataValues($key, $value)
    {
        $this->data_values[$key] = $value;
    }

Super easy. This array was 4 levels deep.