Using Time Model

timemodel

Saving time data into DB

$this->load->model('time_model');
$user_id = $this->session->userdata('id');
$user_timezone = $this->time_model->getTimeZone($user_id);
$format = "U"; // automatically saves it in unix format, this is just to show you that you can adjust format....
$data['timestamp'] = $this->time_model->getUTCTimeStamp($user_timezone, $format);

Shorthand: $data['timestamp'] = $this->time_model->getUTCTimeStamp($this->time_model->getTimeZone($this->session->userdata('id'));

Converting time data to users timezone

$this->load->model('time_model');
$timestamp = $this->db->query("SELECT timestamp FROM table WHERE user_id='$user_id');
//params: 1-> timestamp(assumed in GMT), 2-> users timezone, 3-> time format as specified in date() 
//http://php.net/manual/en/function.date.php
echo $this->time_model->convertTime($timestamp, $user_timezone, 'm-d-Y h:i:s');