Problem uploading picture

hi everyone! I have a profile view in which you can change the profile picture. I'd like to create this behaviour: 
- The relative pic path will be saved in the user table under the avatar column, 
- The actual picture will be saved on the server in assets/profiles folder

So i read the tutorial, and I have some problem making the folder writable apparently (I'm on mac)

PHP Code:

<?php if(is_writable(base_url('assets/profiles'))){
    echo 'writable';
}
else { echo  (base_url('assets/profiles'). ' ' ."is not writable");} ?>

 This code is always returning me that is not writable, but on terminal i have these permissions on the folder: drwxrwxrwx, which I obtained with chmod 777 profiles/

But let's go on... This is my form: 

PHP Code:

<div class="file btn btn-lg btn-primary">
                            Change photo
                            <?php echo form_open_multipart('pages/do_upload');?>
                                <input type="file" name="avatar"/>
                                <input type="submit" value="upload"/>
                            </div> 


This is my controller: 

PHP Code:

public function do_upload()
        {       
                $image_path = realpath(APPPATH . '.uploaded');
                $config['upload_path']          = $image_path;
                $config['allowed_types']        = 'gif|jpg|jpeg|png';
                $config['max_size']             = 10000000000;
                $config['max_width']            = 1920;
                $config['max_height']           = 1080;

                $this->load->library('upload', $config);
                $this->upload->initialize($config);

                if ( ! $this->upload->do_upload('userfile'))
                {
                        $error = array('error' => $this->upload->display_errors());

                        $this->load->view('user/profile/profile', $error);
                }
                else
                {
                        $data = array('upload_data' => $this->upload->data());

                        $this->load->view('upload_success', $data);
                }
        } 


Now, I know that it's not doing what I want (yet), since I'm firstly trying to upload the picture... Later I'll think of storing the path in my table, and deleting the old profile pic, but I think I'm capable of thing it... The problem is uploading the damn picture xD

UPDATE: I keep getting a message 'The upload path does not appear to be valid.' But according to my computer I have permissions... Could it be a problem related to docker or lamp server?