imageUpload.php

<?php
public function uploadImage() {
	$this->load->library('upload');
	$imageFolder = 'assets/images/features';
	if (!file_exists($imageFolder)) {
		mkdir($imageFolder, DIR_WRITE_MODE, true);
	}
	$this->upload_config = array(
		'upload_path'   => $imageFolder,
		'allowed_types' => '*',
		'max_size'      => 2048,
		'remove_space'  => TRUE,
		'encrypt_name'  => TRUE
	);
	$this->upload->initialize($this->upload_config);
	if (!$this->upload->do_upload()) {
		$upload_error = $this->upload->display_errors();
		echo json_encode($upload_error);
	} else {
		$fileNames= array();
		$fileNames= $this->session->userdata('featureImages');
		$fileInfo = $this->upload->data();
		$fileNames[] = $fileInfo['file_name'];
		$this->session->set_userdata('featureImages', $fileNames);
		echo json_encode($fileInfo);
	}
}